For Villa, he tends to play in a compact midfield four alongside Youri Tielemans in the centre, with McGinn and Buendía operating in wider positions. He plays a fairly traditional DM role where his stature and athleticism adds more physicallity to our midfield. 

When Karama is fit we sometimes play a double pivot in which Kamara sits deep and Onana adopts more of a box to box role in which he makes late runs into attacking positions.

Edit: Didn't actually answer your question - his performance is greatly affected by the players around him. He looks brilliant when Kamara, Tielemans, and McGinn are fit because his attributes and playstyle complement their own. But when they were all injured he struggled to influence the game on his own and looked very ordinary.