No it doesn't have to be a black powder rifle scope, any scope will do. Just make sure the scope you purchase can handle the recoil. So I wouldn't get one for a 22lr but I'd get one rated for 30-06 or higher. Hope this helps.

You do not need a scope specically for BP. Just don't get a cheep scope made for an air rifle or .22lr, you want something that can handle the recoil. Nice scope here that won't break the bank >>> https://monstrumtactical.com/1-4x24-first-focal-plane-ffp-rifle-scope-with-illuminated-rangefinder-reticle/ .....Have a great day!

A standard rifle scope would work no issue. It does not need to be expensive and the shock proof Barska Huntmaster would be about perfect for a BP firearm : budsgunshop.com/product_info.php/products_id/60751/barska%2bhuntmaster%2briflescope%2b3-9x50mm%2bwide%2bangle - Cheers and stay safe!