If you’re trying to get into VFX or GameDev then there will inevitably come a point where you will need third-party resources. It’s simply impossible to create everything from scratch and also doesn’t make any sense to do so.
Depending on your project and how much creative freedom you’ll need you might use finished assets or make the mesh yourself but use third-party textures and HDRIs.
Usually, if you’re building a full scene and you’re an individual, then you usually don’t have any other choice than to make use of finished assets. It just doesn’t make sense to re-create a table or pen or book etc. again if there are already thousands out there ready for use.
This list is by no means complete, I will keep updating it as I find new resources. Please let me know if you find something interesting.