How to change pixels per unit for Physics2D and Unity?

Where can I find the settings for changing how many pixels a unit takes for the 2D part of Unity? I can’t find it anywhere, but I read about it all the time.

I assume you’re talking about the pixels to units setting for sprite texture importing. Click on a texture, make sure the texture type is a sprite, and the pixels to units setting is visible. Ideally, you should try to make moving objects have a size of about 1 unit, since that’s what the physics engine works best with. So if a sprite is 100 pixels wide, the default pixels to units setting of 100 is appropriate.

Hello, my 10 years oldson is trying to build a 2D platform video game, he has Unity version 2019.3, he (me neither) cannot figure out how to change the pixel per unit of the tile maps. The tile maps he puts on the grid appear to be tiny, Can anybody help please? Many thanks