Boot Partition doesn't have the correct storage space
You probably had some dual boot config previously and removed the main Windows partition(s). You didn't expand the APFS container disk0s2 afterwards.

A small blocking disk0s3 is a left-over though (right "after" disk0s2). This small partition has to be removed before you can expand your APFS container.


Erase the Microsoft Reserved partition:

diskutil eraseVolume "Free Space" %noformat% /dev/disk0s3

Expand the APFS container:

diskutil apfs resizeContainer /dev/disk0s2 0