How to deal with and simplify over 15 million tris

[Okidoki]

You might wanna look into any auto-re-topo-app/addon like for example (or any other app/thread about this topic):

Quad Remesher auto-retopologizer

Quad Remesher — an auto-retopologizer from the developer of ZBrush ZRemesher — is available for Blender, following 3ds Max, Maya and Modo. Quad Remesher is available for each OS that runs Blender: Windows, macOS and Linux (since December 2020). [Quad%20Remesher%20auto-retopologizer] This thread was initiated several months before Quad Remesher was released for Blender, so only later posts were written after the release, starting with this post. ——————— Ab…