Yes my bully dogs have had curly tails
Like the one on the right? (Not my pics BTW).
If so, that’s a trait of the “sour mug” type English bulldog, which is currently the official breed standard. That comes from the pug that was bred into them early 1800s. Those tails aren’t docked. They’re naturally short and kinked. That’s called the “screw” tail.
Mine are more like the extinct Phil Kuan type, which were the breed standard until the late 1800s. More athletic and functional. They have long tails that are either left in tact or docked. They won’t develop that kink.
The original extinct Old English bulldogs had short ratty tales. One of mine came out with a rat tail so I left it.