It's not easy because the champions league itself isn't all that friendly especially to new teams and I say this cause of the experience I have seen from most teams like Leipzig, Newcastle, and some others and all have failed to make any positive growth and that's why I don't feel any positive achievement will be made to their champions league campaign, but although am not sure for their Laliga journey but the champions league am sure that they will be knocked out.
Like other breakout teams, Girona might find it very hard to cope with the intensity of the Champions league. It's not the Spanish league where they were familiar with all the teams they went up against. All the elite teams play in the Champions league and Girona will have much more on their plates. It's not just girona, but teams that arw prolific in their domestic league don't usually do well in UCL. See the likes or Salzburg or Newcastle as you have mentioned. I'd like to think that teams like that mainly consider their UCL qualification as an achievement and anything after that — getting past group phase, knockout stages, eyc as a bonus. Not to mentioned thru have sold some of their best players.
If I'm not mistaken, this is the first time for Girona to feel the atmosphere in the Champions League. Obviously this is not something easy, because in the Champions League the opponents they will face are also not like the usual teams, there are many big and strong teams that they have to face. In addition, the Champions League also requires a very strong mentality, because it will be very influential when they face heavy pressure. Pressure also does not only come from within the field, but the pressure can also come from outside the field. However, this is a great achievement for them, Girona can prove that they can also be in the Champions League with a struggle that is not easy. I hope they don't miss this opportunity, they must be able to show that they can compete, yes, even though it is something difficult for a team that is not used to it like them.