How is it possible to game on a laptop with a 256 /128GB SSD?

The actual usable amount comes to about say 240/120

If you install GTA V, or Witcher 3 , 65 and 57 GB respectively,

Then on the 128, you have barely 8 GB left for your software which definitely needs more than that.

And on the 256, you get about 128 GB left , but now half of your SSD is taken up by only 2 games.

This means that gaming on a 128 SSD is not practical as if you wanted to install more than 2 big titles, your have to uninstall the installed games.

On the 256, I guess you have enough space left, but does that mean you just have to live with knowing that half your SSD is taken up by only two games.

Context:

I want to get a gaming laptop with a SSD but unless I get one with 512 or 1TB, I don't see how it's feasible to game on 128 or 256

I think I may be missing some obvious detail too, since many laptops have SSD s instead of 1TB HDDs