How about an Isekai tag (literally "new world") ?
This tag could include two suggested tags which are "Reincarnated" and "Teleported to a different world".
My point is that this is one of the main theme from Light Novel and there's more and more adaptation in manga being serialised.
Some good exemple for this tag would be : "Mushoku Tensei", "Tate no Yuusha no Nariagari", "Tensei Shitara Slime Datta Ken", "The New Gate".
Since those kind of series seems to be quitte appreciated and followed here it might be great for their readers to found similare countent easilier.
Btw, pardon me from any english mistake i could have made while writing this, i tried my best .
Agreed, Isekai rather too Many, even isekai tags OUTNUMBERED Music, Medical and Cooking genre.
In these half 2017 over 120 manga with Isekai genre published into manga. This number grow fast 250% in past 5 Years
Even we had Group scans with spesific isekai manga such as LH Translation, Biamam Scans, Champion Scans... ect
In the near future I believe, there is more incoming Manga with Isekai genre.