hey, watch out ! royalty free models from CGTrader dont explicitely allow derivatives.
A retopo is a derivative, and even more, making a LFS mod from an imported 3D model is itself a derivative.
Only use models with license that explicitely allow derivatives.

edit:
check this
https://www.lfs.net/forum/thread/97013-Model-sources---which-are-OK-to-use-and-which-are-not-accepted