I think it might just be a way of seeing your phone is getting old. When I used the Samsung Galaxy Ace 2, when I had it for 3/4 years the battery drained horribly despite little usage. There were some days that I would turn the phone on and it would be dead despite having a full charge the night before. So I think it may be worth just getting a new phone as considering it was released in 2018, battery drain could just be the phone is getting old.
