If you're helping someone who's just turning 18, you're helping someone who's moved to the U.S., first option is a secured credit card. This is a credit card that requires a deposit. That deposit is, of course, refundable, but then it gives access to spend. Important distinction is it is not a prepaid card.
It's similar, but you can take the money out much more easily. And so this is a great option. Another option is a student card. Note that for both of these kinds of cards, anyone under 21 will probably need to have proof of income or a co-signer to get approved.
Some popular cards for people with little to no credit. Chase student cards, but they sometimes need a little bit of history on your credit report. But Discover secured cards, easy. Some Barclays cards have been pretty easy. Surprisingly, Amex cards are quite easy and they do pre-approvals on their website.
This seems counterintuitive because they're usually more premium cards. And I have seen so many au pair mailers offering Amex Gold, Amex Platinum pre-approvals, even with very little credit data, if not any credit data, they're getting some of these pre-approvals.