It is not exactly the best or safest way, probably not the best cost wise either, but I am pretty sure you can buy them from someone else if you make or have a paypal account. Just dont let them know you're buying cryptos.
You have to be 18 to have a Paypal account.
What about just using paypal as the processor? For example, buying something on eBay, and on checkout, just use the pay with debit/credit card option instead of use paypal account option?