In the knockout round of the last 16 of the Champions League, it is filled with the best teams in Europe, I don't think there will be a team that will underestimate its opponent.
In terms of quality, of course Manchester City are the favorites, but that doesn't mean they will easily beat Copenhagen, I think anything is still possible and even if a favorite team loses, it won't be a big surprise in the UCL because we have seen it often in previous seasons.
If an underdog beats one of the favorites this would happen not because they were underestimated but simply because they played the best soccer out of the two teams, since most of the players of those teams not only receive the best psychical training they can get, they also receive psychological counseling to help them overcome those kind of tendencies, so even if Copenhagen does not have the same quality of players that Manchester City has, they will not underestimate them just because of that factor.