Game Assets You Can Use

Lists of (mostly) free 3d assets from popular sources

https://assetstore.unity.com/lists/top-free-3d-models-5063
https://itch.io/game-assets/free/tag-3d
https://itch.io/game-assets/free/tag-Unity
https://www.turbosquid.com/Search/3D-Models/free/unity
https://sketchfab.com/tags/unity3d
https://free3d.com/3d-models/unity
https://www.models-resource.com/
http://www.3dmodelfree.com/
https://www.mixamo.com/#/?page=1&type=Character
https://www.mixamo.com/#/?page=1&type=Motion%2CMotionPack
https://www.pinterest.com/pin/317926054929430908/?lp=true (OK, it's a pinterest board but has good contents)

Audio

Soniss Free Audio Collections GDC18 30BG GDC19 25 GB

McCoy's Collection

Several GBs of 2d assets, low-but audio, and a smattering of 3d assets. Google Drive