I don't know I always disliked most isekai anime. You say Frieren raised your expectation but it is THE OUTLIER. It's one of those anime that has really good overarching theme and relevant setting. The main character is almost a mary sue but you can't help but like her enough because she seems to have very firm belief in something and not for shallow reasons either and she is the central figure that actually carries the plot.

Do you remember anime called Coffin Princess Chaika? It had great premises and compelling mystery but it kind of lost its charm along the way and became a bit forgettable towards the end. Personally I still like that anime but I'm not sure if anyone remembers it. I figure most fantasy and isekai anime have that same kind of quality. It has great premises in the beginning but somewhat loses its plot and becomes tropey. I find it extremely common in Isekai anime especially.