The idea is to gain control over the dark squares and the c5-square.
11.Qxc6? Bxg3 12.hxg3 c4 and the queen is in trouble!

Trying to activate the bishop but White will enjoy a fantastic c5-square and pressure along the c-file!

And Black is in real trouble. White has a lot of ideas, like Rc5 doubling the rooks, followed by Ne5.

I love this move. The knight comes to d3, where it targets c5. Moreover, once the knight is on d3, it can jump to f4, where d5 will suffer more. Another good aspect about Ne1 is that the e2-bishop can be activated via f3, targeting d5, or to g4, where it attacks the knight on d7, one of the defenders of c5.

20...Rbc8 21.Bg4! Qg6 22.Bh3 Rc7 23.Nd3

Nf4 is coming.

Now White targets a7, c7, and c5 at the same time!

Black stopped suffering. Great positional lecture by Viktor!

Nasty along the diagonal. The bishop on c2 was not that effective since after ...g6, Black is covering all the threats along the b1-h7 diagonal.

White is able to play d5 and again we see what devastating effect it has.

Enough for a decisive advantage even though it was not the best option.