How do I limit the lowest resolution of mipmaps?

I am very new to Unity, and I've already seen a thread about this
https://forum.unity.com/threads/limiting-the-amount-of-mipmap-levels.650011/

But I don't understand what to do and I need someone to walk me through it...

I am working on a project/world in Unity 2019 4.30f1 for VRChat and am currently working on optimizing my map.

Currently I have a texture atlas with very generous amounts of bleed (20 pixels and higher) between textures but I still have annoying texture seams/bleeding at a distance because the resolution of the mipmaps are getting waaay to small.

I am not willing to disable mipmaps because it makes the textures look very bad and grainy...

Is there a way to limit the lowest resolution of the mipmaps at a distance so as to stop the bleeding/seams?

 

Picture of the issue in question, note the reddish texture causing the seams at a distance..