In a model with unit setting
mm add a box with dimensions 2x2x2. Now add a PBR material and assign a square texture to the base color. Make sure the texture is set to WCS/OCS (Box).
With the texture size set to 1.0x1.0 you’ll see that the texture will be repeated twice along each edge.
The size with WCS/OCS means the amount of units it takes to go from 0.0 to 1.0 in the unit space.
Now change the texture mapping size to 10.0x10.0. You’ll now see on the 2x2x2 box that you see 1/5th of the texture. You can double-check by assigning the material to a 10x10x10 box.
Note that on the 10x10x10 box I set an OCS frame (you can do that through properties > texture mapping > apply OCS frame panels), because without it the texture would be using WCS (world-coordinate space) mapping, not OCS (object-coordinate space). Here is with the OCS frame removed on the bigger box - the smaller has corner on 0,0,0