Battery, charging board and rear-camera guides are distinct; the charging coil and NFC assembly are also separately documented.
What to check before buying
Charging
iFixit lists a charging board apart from the NFC antenna and charging-coil assembly. Wired and wireless failures can therefore involve different hardware.
Battery and cameras
The battery and rear-facing cameras have separate procedures. The S21 Ultra's modules are not a parts match for newer Galaxy S models.