You'll need to completely master LOD in game engines.

Unity's tutorials are staggeringly bad, but you can easily find them https://learn.unity.com/tutorial/working-with-lods-2019-3#

https://docs.unity3d.com/2023.1/Documentation/Manual/LevelOfDetail.html

You can also easily find literally thousands of tutorials on LOD concepts all over the place. Here's a random one I googled up for you

https://www.youtube.com/watch?v=IIUQE90-gFY

best of luck!