You go into TreasuryDirect, you make a gift purchase for someone else. There is no limit on the amount you can buy as gifts, only a limit on what an individual can get in a calendar year, either from purchasing it themselves or receiving as a gift.

So for example, a married couple can each buy their own $10K for 2022, then buy another $10K now as a gift to deliver in 2023, or even another $10K to deliver in 2024. Buying now for 2024 only adds three months to the lock up period, as the 1 year doesn’t run out til October 2023 anyway.

It’s not hard to do, you just register it in their name and check the “this is a gift” box when you buy it.

TreasuryDirect explains it:

https://www.treasurydirect.gov/savings-bonds/gift-a-bond/