Maybe not a question for a mechanical engineer, but rather for a fabricator or tradesman.
When you spec a hole of a certain size, for a particular fit, you need to know what’s making the hole and what’s fitting into it.
I work in wood, which is looser than metal. Cheap drill bits, or even expensive ones made for wood, can be .020" off size. Let the bit get dull and it will cut a different size hole, depending on the type of bit: a spade bit will more likely rattle a larger hole, while a twist drill will compress fibers instead of cut and leave a smaller one. Drill a hole and measure to be sure.
Likewise, wooden dowels can not only be offsize to a surprising degree, and in either direction, but they can also warp to elliptical— in fact, that’s very common.
I have a large industrial mortiser and hand fit tenons. The difference between too loose and too tight is on the order of .005"
So you don’t think this is just the case for wood, try measuring name brand drills for metalwork and see what you come up with. I’m not sure the effect of sharpness on them.
I would guess that 3D printing depends on the exact formulation, perhaps even the brand, of your medium, the precision of the printer, the temperature of the print head, and the resolution you are working out. As these vary, expect the results to as well.
Check your carbon fiber for tolerance— what’s the manufacturer tell you?
After prototyping and in production, you will perhaps get different results. Talk to the fabricator when you are working up the final file.
For now, consider testing the process or printing small and reaming to fit.
BTW, metric or English, the amount of tolerance is the same. Just convert from one set of units to the other.