Stones or Rico Lewis usually plays as one of the two holding midfielders next to Rodri in a 3-2-4-1 when they have the ball (which is most of the time). However, when they defend, Stones/Rico Lewis plays as a right-back and the system becomes their pretty standard 4-3-3. Akanji, Dias and Aké are the back three in possession usually but when defending it becomes a back four of Stones/Lewis - Akanji - Dias - Aké with Aké being a left-back.
In theory, this system could work for City as Greaves could play the same role as Aké.
Darlow
A. Jones - McLoughlin - Greaves
Christie - Seri
Allahyar - Traoré/Tufan - Slater - Vaughan
Óscar/Tetteh
All theoretical of course though. Liverpool have tried it too with Alexander-Arnold being one of the holding midfielders in possession.