There are at least 3 R sounds.

The scratchy, voiced sound in the back of the throat: as in 'harsh' or 'red'.

The trilled sound as in 'three' or in Irish or Scottish. English speakers the world over may trill the R after th, especially in 'three.'

The inaudible R, as in posh English accents or some American southern accents, where the letter is avoided after a vowel. (Then they make up for it by putting R where it doesn't belong, as in 'area-r.')

There's a comedian who does monologues told by working-class black man named Cla'ance. Some people haven't figured out that Cla'ance is Clarence.

Does anybody know of any other R sounds?