Check out these tutorials:

https://www.forum.creaticode.com/topic/413/3d-using-a-tinkercad-model-difficulty-2
https://www.forum.creaticode.com/topic/652/3d-using-models-from-sketchfab-or-cgtrader-difficulty-2
https://www.forum.creaticode.com/topic/10/creating-your-own-avatar-using-readyplayer-me