Enforcing Fixed/Forced Texture Sizes in Unity

Hello, I'm currently developing a 3D game with a pixelated art style. I have almost all of the art and coding done, but I still can't seem to work around Unity/Pro Builder automatically distorting texture sizes to adjust to the geometry. This has been really frustrating throughout the development and I often will discover through testing that my textures don't align properly to create a pixel perfect appearance. I will pretty much have to continuously redo entire levels as a result of this. Why I'm this far and am still not figuring out what to do is still a mystery to me.

Basically, I want to be able to apply textures and have them appear at the same size with absolutely not stretching or changes in size. I'm using Pro Builder and whenever the geometry gets complex at all, the textures distort.