In the previous season, Barcelona failed in the group phase because they were unable to compete with Bayern Munich and Inter Milan. I don't think that's happening again with them this season. At least it can reach the semifinals or more.
I think it's difficult to measure Barcelona's strength this season because seeing the appearance of their squad hasn't really seen full consistency, but I think it takes time to see Barcelona's strength in the next few matches in the Spanish league, I hope Barcelona also doesn't fail in the group phase and can make it to the UCL final, though hopefully he doesn't end up in group hell.
So far what I see is that Manchester City's most prominent strength is because it seems they are much stronger than last season. It can be seen from the way they play in the EPL this season, it really looks good, especially with the squad that is currently good enough to win back the UCL champion this season, but besides that there is madrid who will also be a threat because madrid has several good players even though they have not yet found the best striker who can replace benzema.
I think the steps of a team in the Champions League stage are determined in the group position, if you join relatively easy clubs then the next step will also be smooth. For now, Barca's strength has not really been read because it is only the beginning of the season in the Domestic League while the UCL is still at the Play Off stage. However, with the addition of players like Gundogan, it is hoped that Xavi's squad can go further in the UCL this season.
There are still many who place Barca in the list of favorites with other big teams, perhaps the historical and mental factors they have are the things that underlie these various assumptions.