Don't renew Ronaldo, and don't take up that option on Morata for 55 million --> extend Morata's loan for an additional season, and let Ronaldo's contract run out (no one is going to pay mega bucks for a 37+ year old - once his contract is up - even if it is Ronaldo. Go all in for Haaland in the summer of 2022, if he's still available.
Regarding midfield, do everything possible to move Ramsey and Rabiot (unjustified huge contracts - bad value for money - minimal output). Bentancur can stay, unless we get a very enticing offer in the region of 35+
Retain McNuggets and give Arthur next season to prove himself/his health. If he becomes another liability, move him in the summer of 2022. Promote Fagioli full time and see what he's capable of.
In defense, it's time for Chiellini to retire. Buffon can stay for another year I guess. Bonucci will stay, whether we like it or not. Keep Demiral and De Ligt, but I fear we might be tempted to sell Demiral if an offer of 40+ comes in. Promote Dragusin and recall Romero (or sell him for Plusvalenza). Danilo has been solid this year - keep him. Keep Cuads because for all his brain farts, he is a solid contributor and one of the few that can make things happen. Sandro has until the end of the season to prove himself worthy; otherwise, move him for 20+
Tek and Dybala to stay. Chiesa and Kulu must stay of course, and Turdeski must be disposed of at all costs. Don't really care about Frabotta, Portanova or Pinsoglio.
If, and it's a big IF, we somehow manage to do the above, then we can reinforce the midfield with both Locatelli (10 million loan + 35 million obligation over 3 years or something) and Aouar (or someone of that level). One midfield acquisition is nowhere near enough. Also, what we currently have in midfield is nowhere near good enough.
After that, try to find a quality FB and a decent backup striker.