Arsenal don’t have to win the Champions League under Arteta, but if Arteta does before he gets sacked, it would be a huge achievement for him. PSG had changed dozens of managers before Luis Enrique came in and won their first Champions League. Enrique won it in his second season at PSG, meaning it takes time to improve the team and win the title they dream of. Arsenal not only need to win the Champions League, they also need to win the Premier League which they haven’t won for a long time.
You cannot compare the performance of Mikel Arteta to that of Luis Enrique because before he won the Champions League, he first started winning the France Ligue 1 title which gave him more confidence to continue with the pursuit of the Champions League title but for Mikel Arteta, the only thing he has done for Arsenal is to finish second for three consecutive seasons without lifting any trophy apart from the FA Cup he won in 2019/2020, his first season as Arsenal's head coach. When Mikel Arteta took over from Unai Emery, we thought that things will take a turnaround for Arsenal but instead he finished 8th position in his first season which was very poor and beyond expectations of fans. December will make Arteta 6 years as Arsenal manager but he could only win 1 major trophy, if he doesn't improve next season Arsenal should sack him and bring another coach. Arsenal needs to be acting like those teams that consistently sack their managers when they didn't perform well in a season because if they take in that habit, they can possibly sign a coach that will break their deadlock and win either the Premier League title or the Champions League title.