To be able to win the Champions League trophy is not an easy job, let alone Arsenal, even PSG are still unable to do it. We realize that every team has the opportunity to win the Champions League trophy, including Arsenal, but it is better for them to focus on the Premier League first. In my opinion, Arsenal will have the opportunity to compete with the Champions League favorites in the future, once they are truly able to conquer the Premier League. Arsenal has shown signs of success, Arteta needs to maintain his squad performance so that it does not decline, and start next season more impressively.
There is still a lot to improve if Arsenal is to win the Champions League. I have to admit, in the last few seasons Arsenal have experienced an improvement in performance, but they also still have weaknesses in terms of their inability to maintain consistent performance. Arsenal often slip up in games they should be able to win, these mistakes make them always unable to compete with Manchester City in the race for the EPL title.
To win the UCL you need a squad that is able to maintain its performance in every match. Arsenal must learn more from the success achieved by Real Madrid and Manchester City if they want to win this most prestigious championship. Arsenal still needs time to compete with Real Madrid or other big clubs, maybe it's true as you said, Arsenal should focus on the EPL first, when they are able to win the title, they can increase their target to the UCL.
The competition in the Champions League is very competitive and even much tighter than what happened in the English League, especially when the match has entered the knockout stages, so it does take many factors to be able to compete until the Champions League final match, Arsenal we must admit that they have experienced a lot of improvement in their performance and also their consistency in the league even though they often lose focus in crucial matches in the league, but I think the improvement that has occurred to Arsenal still does not make them worthy of being the favorite to win the Champions League, as I said before, currently Arsenal does not have a mentality that is indeed an important factor in winning the Champions League or even the League, we can see how teams like PSG continue to fail in the Champions League even though their squad is full of star players so far but the mentality they have is no better than arsenal at the moment, arteta needs to continue to improve the mentality possessed by the current Arsenal players apart from improving the quality of their squad.