Back-to-back title is quite possible for Manchester City when we think about it on paper. Because technically they have one of the best squads in Europe now. And they are playing according to Guardiola's really solid system as well. However this task is still going to be quite difficult for them at the same time.
The reason why is that they have really challenging opponents such as Bayern Munich and Real Madrid. Manchester City won the title for the first time in their history previously. It would be really challenging to retain the title against these more experienced teams.

De Bruyne and Haaland are needed as a duo for Manchester City from now on to increase their chance.
Manchester City's performance is very good, so in my opinion, I don’t think Real Madrid and Bayern Munich are going to be problems for Manchester City, although I obviously know that these two teams are very good and their performances are going well. But I think Manchester City is quite doing well when compared to these two teams, which are Bayern Munich and Real Madrid. However, Gaurdiola is a very good manager; he has different strategies for his squad when playing, and it always favours them. Therefore, I think Manchester City will be challenging for these teams.
Again, Manchester City winning last season doesn’t mean they won't be able to do better and win title again. We know that the reason why these teams have been shining since the beginning of the season is due to the absence of Manchester City key players. Now that they are back, everyone is saying that they will be the favourites because we know that if Halaand and Kelvin De Bryune are around, the Manchester City squad is good to go.