Toilet bowls themselves generally only need to be replaced if they are cracked, although different parts within the toilet may need to be replaced more frequently.
These parts include:
The toilet handle: There is no specific lifespan for your toilet handle, but it should be replaced if you have to jiggle it to stop it from running, your toilet won’t fully flush unless you hold it down, or your water continues to run without you flushing.
Flappers, trip levers, fill valves, and plumbing connections: These all have a similar lifespan of about four or five years.
Wax seals: These tend to last around 20-30 years.