If you choose the base version of the S23 at 128 GB, then a little more than half will be available.
This is due to the number of pre-installed Google apps, One UI 5.1 shell and Samsung services. And yes, you won’t be able to delete most of them. The number of pre-installed programs may also vary by region.
By comparison, Android 13 on the Pixel 7 is about 15GB, while the full Windows 11 for PC is 30GB.
There is only one conclusion: if you are going to buy a new Samsung smartphone, then there is no point in considering the basic version.