With the defensively minded Cardoso (a very specialist DM role) we need in a CM3 :
1. An AM such as Maddison, Kulusevski or Donley
2. A 6/8 hybrid such as Bergvall or Bentancur or Devine, I think Gray would be fine too as he's very versatile, less sure that Sarr is a great partner as whilst athletic he's not other great other attributes. Cardoso will need help as a DM from time to time as well as someone able to set attacks going so a 6/8 hybrid is a necessary partner for him.
Playing alongside a proper #6 will bring out the best in Sarr.
.........Classic high energy box 2 box player that chips in with goals.