The ear tips have a documented tool-free replacement route and five fit sizes. That service does not extend to the earbud battery.
What to check before buying
Replaceable tips
iFixit's Pro 3 guide covers worn or lost silicone tips, with no tools required. Apple supplies XXS through L sizes, so fit and acoustic seal can be restored without replacing the earbuds.
Other wear
The documented guide is for ear tips, not an internal battery. AirPods Pro 3 have a USB-C charging case and distinct earbud and case model numbers, which should be checked when buying a replacement unit.