I don't watch a lot of isekai. Not a lot of anime in general; watching TV in languages I don't speak takes a lot of spoons these days, between reading the subtitles, watching the action, trying to catch the subtleties of an unfamiliar culture in the voices and animation...
...and isekai specifically is built on a formula that's Kinda Not for Me. But the genre has existed for long enough that I occasionally catch wind of shows that play with that formula.
@WizardOfDocs some friends on Discord were recently talking about "which is older: magical girl or isekai", and my takeaway from reading that conversation was "it's hard to know which stories are older when they come from a time of oral tradition rather than being written down". This group maybe has loser genre definitions than the norm, but they did point to an isekai in Gilgamesh.