In this position 1.d4 Nf6 2.Nf3 g6 3.c4 Bg7 4.Nc3 0-0 5.e4 d6 6.Be2

Normally the blacks play 6… e5 with future attack in the side of the king and the whites attack in the side of the Lady.

Case the blacks play 6…c5 which must be the plan of the whites? Must be advanced d5?

Not necessarily. I believe that transposing into a Maroczy bind is also a viable option.

Reasonable tries by white would include:

7.d5
7.0-0
7.h3
7.dxc5

Crash

Batsford printed 2 books on the King's Indian in the late 60's & 70's.
The older book was a massive work on the entire King's Indian, which included
the Tchigoran Indian and other set ups.
The later version was very similar to MCO, but updated and contained material
of what GM played at the time. NIC also printed an Indian version.
East German (Berlin) printed a volume on the King's Indian as well if I recall by Boleslavsky.
Ideas in the Indian: When White plays 7. h3 the idea is play the QB to e3.
An idea expounded in Reshevsky, and Najdorf games, and probably could be seen in a Tournament book from 1953 by Bronstein.
When White goes for d5, the idea for Black is Na6, and c7.
Since these days data bases are the thing, refer to Chesslive.de and play
each move. The exponents of the Indian Defence were Reshevsky, Najdorf,
and a host of Soviet masters. The Yugoslav players also gave it a try.
For paper copies see the ECO book on the Indian Defense.
I myself used to prefer the Saimisch Variation 5.f3

I have also reached similar positions, but through transposition, i listed the moves below. Here is one of them. "the sicilian" I believe Black should exchange his c-pawn for white's d-pawn because his fienchettoed bishop on g7 attacks (potientially threatens) whites knight on d4 after his knight on f6 is moved. However, I am not so sure of d6 immediately, i would play 0-0 instead, here is the position.

1. e4 c5
2. Nf3 g6
3. d4 Bg7
4. c4 cxd4
5. Nxd4 Nf6
6. Nc3 0-0

The following are the first two games in CB. The variation above, playing like a Sicilian has been known since 1936.
[Event "Trebitsch mem 19th"]
[Site "Vienna"]
[Date "1936.10.19"]
[Round "1"]
[White "Fuster,Geza"]
[Black "Opocensky,Karel"]
[Result "1/2"]
[Eco "A31"]
1.d4 Nf6 2.c4 c5 3.Nf3 g6 4.Nc3 Bg7 5.e4 cxd4 6.Nxd4 0-0 7.Be2 d6 8.0-0 Nbd7
9.Be3 Nc5 10.f3 Bd7 11.Qd2 a5 12.Nb3 Nxb3 13.axb3 Bc6 14.Nd5 Nd7 15.b4 e6 16.Nf4 axb4
17.Qxb4 Rxa1 18.Rxa1 Qf6 19.Rd1 Qxb2 20.Qxb2 Bxb2 21.Rxd6 Ra8 22.Rd1 Ra2 23.Kf1 Be5 24.Nd3 Ba4
25.Rb1 Ra1 26.Rxa1 Bxa1 27.Nc5 Nxc5 28.Bxc5 g5 29.Kf2 1/2

[Event "Buenos Aires ol (Men) fin-A"]
[Site "Buenos Aires"]
[Date "1939.09.??"]
[Round "13"]
[White "Zita,Frantisek"]
[Black "Prins,Lodewijk"]
[Result "1-0"]
[Eco "B39"]
1.c4 Nf6 2.Nc3 g6 3.e4 c5 4.Nf3 Bg7 5.d4 cxd4 6.Nxd4 Nc6 7.Be3 Ng4 8.Qxg4 Nxd4
9.Qd1 Nc6 10.Be2 0-0 11.0-0 d6 12.Qd2 Ne5 13.f4 Nd7 14.Rad1 b6 15.Bf3 Bb7 16.e5 Bxf3
17.Rxf3 Nc5 18.exd6 Qxd6 19.Qxd6 exd6 20.Bd4 Rfe8 21.Bxg7 Kxg7 22.f5 Rad8 23.h3 Ne4 24.Nb5 g5
25.b3 Rd7 26.Rfd3 Kf8 27.g4 a6 28.Nd4 Nc5 29.Rc3 d5 30.b4 Na4 31.Rc2 Rc7 32.cxd5 Rxc2
33.Nxc2 Re2 34.d6 Ke8 35.d7+ 1-0
Later games by Taimonov and Geller:
[Event "URS-ch33"]
[Site "Tallinn"]
[Date "1965.12.??"]
[Round "13"]
[White "Taimanov,Mark E"]
[Black "Lepeshkin,Vladimir"]
[Result "1-0"]
[Eco "B37"]
1.c4 g6 2.Nc3 Nf6 3.Nf3 Bg7 4.e4 c5 5.d4 cxd4 6.Nxd4 Nc6 7.Nc2 d6 8.Be2 0-0
9.0-0 a6 10.Kh1 Be6 11.Bd2 Qb8 12.a4 Rc8 13.Ra3 b6 14.f4 Ra7 15.Qe1 Na5 16.b3 Bg4
17.Bxg4 Nxg4 18.Nd5 Nc6 19.Bc3 Bxc3 20.Qxc3 e6 21.Nce3 Nxe3 22.Nf6+ Kf8 23.Nxh7+ Ke7 24.Qxe3 Rh8
25.Ng5 Rh5 26.Ra2 Rd7 27.Rd2 f6 28.Nf3 b5 29.cxb5 axb5 30.e5 fxe5 31.Qe4 d5 32.Qxg6 Rf5
33.Rc1 Qb6 34.Rdc2 Nd4 35.Qg7+ Ke8 36.Rc8+ Rd8 37.Nxe5 1-0

Later games by Taimonov and Geller:
[Event "URS-ch33"]
[Site "Tallinn"]
[Date "1965.12.??"]
[Round "13"]
[White "Taimanov,Mark E"]
[Black "Lepeshkin,Vladimir"]
[Result "1-0"]
[Eco "B37"]
1.c4 g6 2.Nc3 Nf6 3.Nf3 Bg7 4.e4 c5 5.d4 cxd4 6.Nxd4 Nc6 7.Nc2 d6 8.Be2 0-0
9.0-0 a6 10.Kh1 Be6 11.Bd2 Qb8 12.a4 Rc8 13.Ra3 b6 14.f4 Ra7 15.Qe1 Na5 16.b3 Bg4
17.Bxg4 Nxg4 18.Nd5 Nc6 19.Bc3 Bxc3 20.Qxc3 e6 21.Nce3 Nxe3 22.Nf6+ Kf8 23.Nxh7+ Ke7 24.Qxe3 Rh8
25.Ng5 Rh5 26.Ra2 Rd7 27.Rd2 f6 28.Nf3 b5 29.cxb5 axb5 30.e5 fxe5 31.Qe4 d5 32.Qxg6 Rf5
33.Rc1 Qb6 34.Rdc2 Nd4 35.Qg7+ Ke8 36.Rc8+ Rd8 37.Nxe5 1-0

[Event "Lugano ol (Men) qual-A"]
[Site "Lugano"]
[Date "1968.10.17"]
[Round "5"]
[White "Geller,Efim P"]
[Black "Bandal,Rosendo"]
[Result "1-0"]
[Eco "B38"]
1.Nf3 Nf6 2.c4 c5 3.Nc3 g6 4.d4 Bg7 5.e4 cxd4 6.Nxd4 d6 7.Be2 Nc6 8.Be3 Bd7
9.0-0 0-0 10.Qd2 Nxd4 11.Bxd4 Qa5 12.Rad1 Rfe8 13.Rfe1 Rac8 14.Bf1 Bc6 15.f3 a6 16.Kh1 Nh5
17.Bxg7 Nxg7 18.a3 Ne6 19.b4 Qe5 20.Nd5 Nc7 21.Qf2 Ba4 22.Rd3 Nxd5 23.exd5 Qf5 24.Rde3 Rc7
25.Qh4 Qc2 26.f4 b6 27.Bd3 Qd2 28.f5 Bc2 29.f6 h5 30.Qg5 Kh7 31.Qxh5+ 1-0

Interesting the idea to transpose for the Marozcy, also I am preparing the English pra to prevent the Benomi and the Benko and has variants that the blacks can transpose for the Marozcy.

But coming back to the projects of the King´s Indian, the blacks can opt to Bg4 with or without c5 and falling in other positions. What plain vocês suggest?

For example:

1.d4 Nf6 2.Nf3 g6 3.c4 Bg7 4.Nc3 0-0 5.e4 d6 6.Be2 Bg4 7.O-O c5

[Event "Barcelona simul"]
[Site "Barcelona"]
[Date "1935.12.??"]
[Round "0"]
[White "Llado Lumbera,Jaime"]
[Black "Capablanca,Jose Raul"]
[Result "0-1"]
[Eco "E91"]
1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 0-0 5.Nf3 c5 6.Be2 d6 7.0-0 Bg4 8.Be3 Nc6
9.h3 Bxf3 10.Bxf3 Nd7 11.d5 Nd4 12.Be2 e5 13.Bd3 f5 14.f4 fxe4 15.Bxe4 Bh6 16.Bxd4 cxd4
17.Nb5 Nc5 18.Bc2 exf4 19.Kh1 f3 20.Rxf3 Rxf3 21.Qxf3 Qh4 22.Rf1 Rf8 23.Qe2 Rxf1+ 24.Qxf1 d3
25.Bxd3 Bf4 0-1

[Event "URS-chT"]
[Site "Moscow"]
[Date "1959.08.06"]
[Round "0"]
[White "Geller,Efim P"]
[Black "Spassky,Boris V"]
[Result "1/2"]
[Eco "E91"]
1.Nf3 Nf6 2.c4 g6 3.d4 Bg7 4.Nc3 0-0 5.e4 d6 6.Be2 c5 7.0-0 Bg4 8.d5 Nbd7
9.h3 Bxf3 10.Bxf3 Ne8 11.Be3 e6 12.dxe6 fxe6 13.Bg4 Qe7 14.f4 Bxc3 15.bxc3 Ng7 16.Qd2 Nb6
17.Qd3 Rad8 18.a4 d5 19.cxd5 exd5 20.Qb5 d4 21.cxd4 Qxe4 22.Bf2 cxd4 23.a5 Nc8 24.Rac1 Nf5
25.Qc4+ Qd5 26.Bxf5 Rxf5 27.Bxd4 Qxc4 28.Rxc4 Rxa5 29.Rfc1 Rad5 30.Rxc8 Rxd4 31.R1c7 b5 32.Rxd8+ Rxd8
33.Rxa7 Rb8 34.Kf2 b4 35.Ke3 b3 36.Ra1 b2 37.Rb1 Kf7 38.Kd4 Ke6 39.g4 Rb4+ 40.Kc5 Rxf4
41.Rxb2 Kf6 42.Rb7 h6 43.Rb6+ Kg5 44.h4+ Kxg4 1/2

[Event "Madrid zt"]
[Site "Madrid"]
[Date "1960.??.??"]
[Round "12"]
[White "Gligoric,Svetozar"]
[Black "Walther,Edgar"]
[Result "1-0"]
[Eco "E91"]
1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Nf3 0-0 6.Be2 c5 7.0-0 Bg4 8.d5 Na6
9.Bf4 Nc7 10.Qd2 Re8 11.Rfe1 a6 12.e5 Nh5 13.Bh6 dxe5 14.Nxe5 Bxe2 15.Rxe2 f5 16.Bxg7 Kxg7
17.f3 Rf8 18.Nd3 Qd6 19.Qe3 e6 20.Qxc5 Qxc5+ 21.Nxc5 exd5 22.Re7+ Rf7 23.Rxc7 1-0

In the game Zita x Prins, I better find to play 7.Be2 in the place of 7.Be3 not to enter in the variants with 7… Ng4.

[Event "Buenos Aires ol (Men) fin-A"]
[Site "Buenos Aires"]
[Date "1939.09.??"]
[Round "13"]
[White "Zita,Frantisek"]
[Black "Prins,Lodewijk"]
[Result "1-0"]
[Eco "B39"]
1.c4 Nf6 2.Nc3 g6 3.e4 c5 4.Nf3 Bg7 5.d4 cxd4 6.Nxd4 Nc6 7.Be3 Ng4 8.Qxg4 Nxd4 9.Qd1 Nc6 10.Be2 0-0 11.0-0 d6 12.Qd2 Ne5 13.f4 Nd7 14.Rad1 b6 15.Bf3 Bb7 16.e5 Bxf3 17.Rxf3 Nc5 18.exd6 Qxd6 19.Qxd6 exd6 20.Bd4 Rfe8 21.Bxg7 Kxg7 22.f5 Rad8 23.h3 Ne4 24.Nb5 g5 25.b3 Rd7 26.Rfd3 Kf8 27.g4 a6 28.Nd4 Nc5 29.Rc3 d5 30.b4 Na4 31.Rc2 Rc7 32.cxd5 Rxc2
33.Nxc2 Re2 34.d6 Ke8 35.d7+ 1-0

MALBASE thanks for the games