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.
But not a Bitcoin wallet. Bitcoin is liberating for youths as it is also liberating for those denied access to modern banking (ie. the poor of the world).
Don't listen to the advice of adults telling you how to act and behave, my child. Know that most of the adults in this world are already insane, as a result of their enduring exposure to the insane culture of civilization. Worse, they think themselves your masters.
They think they own this world until you inherit it from them, but this could not be further from the truth. They (we) are borrowing this world from you, the next generation. And we're treating it with the utmost disrespect. The younger you are, the purer and truer your wisdom.