Good luck at UCL next year, Sevilla.
Sevilla will play in the Champions League as European League champions, and this will not be the same for Sevilla, and it is doubtful that they will be able to impress in providing tough resistance to their opponents later, especially if they are able to pass through the group phase, because the Champions League is more competitive because the best team in the league will compete for something prestigious, maybe if Sevilla make changes in the squad they will be able to compete more but with the current squad I doubt there will be a lot of things they can do, so like in the European league they are doubtful but able to answer doubts by lifting trophies but in the champions league everything will be very different. Sevilla must be willing to spend a lot of money to strengthen their squad but that is if they have it, because every club has different financial capabilities.
To be honest, I don't mean to belittle Sevilla. however, the fact is that the final between Sevilla and AS Roma is not as interesting as the other finals. for example, FA Cup, DFB Pokal. that is, the two teams that competed in the final of this competition did not really have good quality of play.
Well, speaking of matches in the Champions League later, I agree with what @Strongkored said. I'm sure Sevilla won't survive in a more prestigious competition with the existing squad. however, if Sevilla's management makes a lot of changes. I mean, strengthening his team by bringing in newcomers with more potential, at least Sevilla can compete a little with teams at their level. but if not, don't expect Seville to run smoothly. even though Sevilla made many changes to their squad. even then, it does not promise that they can qualify in the group phase. which in essence, Sevilla had to make a lot of changes because what they showed in this competition was more about luck.
The DFB Pokal wasn't any better than the Europa League final. I think the Europa League final was as intense as expected physically and Sevilla did play well and Roma at least gave their best to play and not to lie around on the ground all the time. Depending on where you are coming from of course, but I think the Europa League final is in between the FA Cup and the DFB Pokal. A game between Manchester City and Manchester United is always a highlight whereas a game between Frankfurt and Leipzig is ok, it is not a game everyone would want to watch on a casual Saturday all around the world. But a Europa League final between Sevilla and Roma did probably attract a lot of people and the game was an interesting, exiting fight. As I said, i wasn't so much about the FA Cup itself, but about the teams. If it is Manchester City against Fulham in the FA Cup, it wouldn't be as interesting.