The City game was one game. You could also look at the PSG game where they were ripped apart and I think it finished 5-0 at home. I'd say player for player Huddersfield and Brighton are probably stronger. Lossl, Gross, Mounie, Kongolo, Mooy just to name a few from Huddersfield that would walk into Celtic's team and they only survived by the skin of their teeth. You could question whether that qualifies as 'holding their own'. Celtic would also have to completely change their style of play to pick up points as they wouldn't be the favourites or dominant possession wise in too many games, which would be another challenge for them.
Of course if Celtic had the Premier League TV money they would have a good chance of doing well. Many teams have proved in the past that it isn't that easy but I think we were meaning Celtic as they are currently.