This is another season and just like Real Madrid, all other top teams are building up a strong team in order to stand a good chance for the title. Arsenal is having a good time now, so winning the premier league again next season may not be a problem to them and will dominate all other teams like they did this season. The champions league is something they’ll want to try to win also, after seeing themself making it to the finals of the champions league this season. There is nothing that is impossible for them, they just have to try it out and see how far they can go in the competition and possibly try to win it next season.
You're right, Arsenal played very well this season in the Champions League and managed to reach the final,, even though they ultimately lost to PSG. However, Arsenal will certainly be more confident in the coming season and be even more aggressive in the Champions League. Because they have experienced all the ups and downs in the Champions League the previous season, so they certainly have enough experience to be able to dominate again in the upcoming Champions League. But even so, I don't think it will be easy for Arsenal to advance to the final in the coming season, because in essence, they are not the only ones who want to be champions in the Champions League.
But other big teams also want the same thing. For example, PSG intends to win again in the coming season, so they will certainly train diligently to improve their performance. Furthermore, Real Madrid and Barcelona certainly won't be sitting idle either, as they too want to win the title. So, the bottom line is that Arsenal's in the Champions League next season will clearly need to be even better if they want to have a strong chance of winning.