There's a bug in singleplayer, that if you unclaim your griffin, then leave and rejoin, it will turn into a normal wild griffin, except the only thing different is that it still has the stats from when it was tamed (and also it will be boosted by any soothing balms if you used one on it when you tamed it)

Then, you can knock out, and tame your griffin again and the exp will be reset back to 0.

Of course this only works in old ark mobile, and do with this information what you may.