By carefully stretching the definition of an episode we could argue that Melancholy of Haruhi Suzumiya S2E1 has runtime of over 3 hours.

97 minutes

At that length, I think I'd call it a movie/film even if it's part of a TV series's progression.

If we're including Japanese anime films in general, In This Corner of the World is supposedly the longest at 168 minutes for the extended version, followed by Final Yamato at 163 minutes, and then The Disappearance of Haruhi Suzumiya at 162 minutes -- according to this list on Wikipedia.

Frieren ep.1 to 4 were 4 episodes but were premiered on TV as a quadruple feature at around 2 hours minus advertisement time.

That episode where Frieza was gonna destroy Piccolo's homeworld in like thirty seconds but it was really like 30 days

Attack on Titan final episode is 85m.

Does the Garden of Sinners series count. I mean that's all movies with the longest 120 minutes. But it's kind of a very long series

There's a few episodes of Detective Conan/Case closed that aired as 2 hour long specials. The longest I can find rn with just a quick search would be episode 345 at about 117 minutes.

Demon Slayer: Infinity Castle is 156 minutes

I vaguely remember that I did not watch the anime adaptation of Atelier Ryza because the first episode was 3x (4x?) normal length, which should be >60 min.