there are some binderies that do thesis binding, from single sheets and in a simple buckram cover. these can be fairly affordable, but they are like library bindings, designed for wear and tear.

you should be able to find one locally if you are near a college/university.

there are also online options, like this. No affiliation, and it's only the first that popped up.

but they have other options (nicer covers, etc.).

the difficulty with a paperback is thickness. and that it has already been trimmed. when sheets are loose, as they'd be when sliced off from a paperback binding, they don't have much structural potential. a real hard-bound book usually has folded sheets, some amount of sewing, etc.

regardless, there are a LOT of options.

you could even approach a traditional hand bookbinder, and commission something. but we're talking much ca$h. multiple hundreds to thousands.

depends whether this is something to just wear better than a paperback, or an heirloom obkect. ...and of course, something in between.