If it just takes place on another world with no transfer or reincarnation involved that's just a normal story. Unless you're going to tell me that Lord of the Rings is an Isekai.
In the strict sense of the japanese word it is.
I'm going to go totally off in the woods here, tl;dr forgive me... 'Isekai' has at least three different meanings.
First, like Elhao said, literally it just means 'another world' so anything with 'another world' would qualify. But it's not really used that way.
Second is 'transported to another world'. Under this interpretation our earliest Scifi/Fantasy work is Isekai. People have been writing about normal people traveling to fantastic lands for thousands of years. One of the first movies, A Trip to the Moon, qualifies. ERB had John Carter of Mars where he is literally just randomly whisked away from a cave to Mars, and with his cheat skills (used to higher gravity) and Earth knowledge he becomes super powerful ruler with the hottest Mars chicks. Also Pellucidar which is technically just Earth center but is effectively another world. HP Lovecraft did tons of things where normal Earth guy goes on cruises to fantastic worlds with magical cats. Tolkien's Narnia and Venus series are 100% this isekai. Manga where fantasy people get brought to Earth is also isekai here, or 'reverse-isekai'. You could KIND of even argue that the Silmarillion (and thus Lord of the Rings) is isekai because it's all about fantasy people coming to Middle Earth from out of the west and being OP. But while Silmarillion is told from their perspective, LotR is not.
Third is 'all the modern Japanese isekai tropes'. 99% of Isekai is total loser who everyone thinks was the weakest gets isekaied / kicked out of his party / is betrayed / is exiled / his parents spurn him but (surprise!) he was actually the strongest!1 And builds his slave cheat harem. 100% undiluted wish fulfilment. There's the girls' version of this too, though it tends to avoid cheat slave harem (aw) and go for 'marries the often yandere prince / king' . This is all SO cliche that even when I run into a fantasy manga with these tropes that's not technically isekai I just lump it under 'isekalike', kinda like a 'roguelike'. I would argue here that LotR is not Isekai even though Bilbo leaves his little world for a larger fantasy world because neither Bilbo or anyone else ever becomes OP.
Anyhow, this seems to be under the second definition. His cheat skill is knowing Japanese cooking, but (so far) he's just running a little inn in the middle of nowhere.