The Files endpoint might be of use:
When I ran it against an arbitrary library, it indicated a lot of 0 file sizes, so ymmv.
You can call an endpoint like Siddharth shows. In the results of the call I've indicated, there is an endpoint to call for the specific file. It will look something like:
So you could call the initial Files endpoint I referenced, then depending on what you are doing, call the individual file endpoint for further information