On mobile in the strong cave just run past them if u can. U don't have to worry about purlovias or polar bears so just jump and run. On the other hand an easier (but slower) way is to hit option when u see them and quit to menu. Save ur progress in a backup save if u wanna be absolutely safe then return to game. U should find the cave clear or, in the room with the floating ice chunks, mostly clear. I recommend using the second option for your first time since there's at least two crystal patches blocking access to the artifact. After the first run the crystals won't really reappear and you will face a lot fewer animals.
My ARK Mobile file is set on easy difficulty (I really wish you could change your game’s difficulty on mobile) and found a yeti. I looked at it through my spyglass, and it was level 80+. Even if you are on easy difficulty, they are very high level. Same goes for all the creatures in the Northern Cave. Don’t go in there without packing some sort of mastercraft ranged weapon, but I wouldn’t do it with a shotgun. Make sure there is distance between you and the yeti before engaging. Btw I never tried fighting the yeti I only had a primitive fabricated pistol