He installed Julian Alvarez in De Bruyne's original position. If you saw him in the first game earlier this season. Although at that time De Bruyne did play but in double pifot with Rodri. But it turned out that his hamstring had not healed properly and he only played 23 minutes. Against Newcastle, Julian Alvarez was back in the same position.
I don't think Julian Alvarez plays in the same position as De Bruyne. When he played together with Haaland, he will play as a second striker (SS). While De Bruyne always plays as attacking midfield (AMF). Actually, Man City have Bernardo Silva and Cole Palmer who play in the same position as De Bruyne. So, Pep Guardiola doesn't need to force Julian Alvarez playing as attacking midfield (AMF). Ideally, if Bernardo Silva is available, he is the right person to change the role of De Bruyne. He plays in the same position and has almost the same level as De Bruyne, too.
Although Julián Álvarez can contribute well as an attacking midfielder, I don't think he is comfortable in that role. Julián Álvarez has a high desire to score goals instead of helping other strikers score goals, so I don't think he is right for the role of an attacking midfielder.
Julián Álvarez will never play comfortable as attacking midfielder, he is a striker. I'm sure Guardiola won't force him to play as attacking midfielder if Bernardo Silva and Cole Palmer are available in the squad. Unless these players got injured, so Guardiola must have an alternative to change the formation or try to put Alvarez as an attacking midfielder.