Not in the traditional sense, Megan returns to the human world whenever she pleases.

7955845
While it does possess some of the basic elements of an Isekai, it isn't .

Like 7955848 says, Megan is able to go back and forth between the two worlds.

So, it's somewhat similar, but not the same.

7955858
Only in the most basic idea, IE "other world" Megan does indeed explore a "real" universe separate from her own.

But it's separate from the modern focus of the idea used in say anime of the protagonist being overpowered, or becomes overpowered very quickly, with the hero not really being challenged.
Megan is the POV character, but most of the episodes focus on the ponies.

7955861
That's what I started to notice not long after being introduced to the Isekai concept.

In truth, this first show is a "two worlds" type of scenario. There were more than a few of those back then now that I think about it.

Not many now though, characters are generally confined to one world and don't move back and forth anymore.

The Dungeons and Dragons cartoon, now that was an Isekai, only without overpowered main characters.

7955867
And like most early appearances of the idea, was an unbuilt trope.
The protagonists had decent lives, and wanted those lives back.
Ironically, one fan variance of the D&D cartoon finale (never animated by the studio itself) had Presto being the only one who both found love in the Realm and also found something he was good at that doesn't exist in our world (magic) and was able to build a life for himself, while his friends jumped at the chance to go home, but accepted Presto's choice to remain in the Realm.

7955868
It was very unbuilt trope back in the early 80s. It was also extremely uncommon too.

That is the only example I currently remember. I have little doubt there were others.

I can see the series ending in that way too. It feels like a very natural conclusion to the D&D show.

I do have an actual MLP Isekai set in Ponyland for an idea myself. It's still in very early pre-production though.

I've also dumped the overpowered protagonist idea, those are boring.

7955873
Those exist because the Japanese salary men who watch Isekai are powerless surrounded by bullying arrogant superiors while their years of hard work have apparently yielded them nothing, and they're desperate for companionship and just want to escape from all of it.

It's not just entitled teenagers who like this stuff.

7955886
It takes all kinds.

Personally, I like my main characters to have substance.

7955919
Oh I agree totally and utterly and completely.

7955921
It does make things more interesting, and engaging.

7955938
It's what I tried to populate my original world with.

7955941
Same. It's not easy, but worthwhile.

If I knew what this word meant, I could answer this question.