Depends on the brand. Rip Curls fit me right, same size on Oneill - no go.
I would listen to your body - any pain, and I mean beyond "uncomfortable". Go up a size.
If they're brand new, and just tight, snug, but not causing pain - they will def stretch out.
Give them some time. Mine were a Lille too snug as you described and they eventually broke in. Keep your nails trimmed though. The tight fit could give you ingrown nails otherwise.
Another thing to do is seat your heel as deep into the heel of the boot as you can. it does give more room in the toe area and helps shape the boot to your foot. Alas a better fit