1. Do you ever - in your day-to-day life now, do you do this? Oh, you live next door to a ranch? Do you ever get to ride a horse? (Note I'd actually say "go riding" for horseback riding, but for this exercise, let's leave it alone.)
2. Have you ever - up until this point in your life, and maybe you still will in the future, have you ever done this? From the time you were 2 or 3 until today? (And you still may tomorrow or next year or in 2040.)
3. Did you ever - I'd only use this to refer to a specific time in the past when horseback riding was a like thing to do.
Remember when you said you were going to that dude ranch for your vacation? Did you ever do that? Did you ever get to ride a horse?
or: Hey, back in 2003 when you rented a room from that guy who owned the barn, did you ever get to ride any of the horses he owned?
Despite what you hear about Americans never using the present perfect and always using the simple past, it would not sound right to me (an American) to say "Did you ever" as a replacement for "Have you ever."
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