I have recently purchased a mini pc and it only has 16gb of storage and I wanted to know if it was possible to get a version of windows that takes up less than 16GB of storage? Even if it's only 32 bit
No.
After a basic WIN 10 Home install, it may consume 11GB.
However....to do the install, it requires 20GB free space.
Then, actually using this system, even if the base OS only consumes 11GB....you then have pagefile, temp files, etc, etc.
Then, any Windows update will fail. Especially the semi annual Feature update.
What OS did it come with originally?
How much RAM is in it?