There are 2 players that could be sold: Pogba (Madrid and Juventus interest) and Lukaku (Inter interest).
If we sell Pogba, we can invest the money in 2 players. Most of the money should go for a creative/goalscoring midfielder, someone like Havertz, Eriksen, Fernandes or Maddison.
Then, we should get another midfielder. It could be a deep-lying playmaker (Neves/Tielemans), a box-to-box (N'Domebele/Barella) or even a destroyer (Rice/Ndidi).
If we sell Lukaku, then we should use the money to buy a RW, the best options at the moment are Chiesa and Pepe, considering that Sancho will stay at Dortmund.
It seems that we are going to end up with Wan Bissaka for 50m. So I would sell the deadwood and use the rest of our transfer budget to get a top CB like Koulibaly.
At the end, we could have: Koulibaly, Wan Bissaka, N'Dombele, Fernandes and Pepe (I think Chiesa will go to Juve). That's 5 quality players for the first team.