you can find a solution on opensource.com ,,, here is an extract :To configure a vanity onion address, you need to generate a new private key to match a custom hostname.

Two applications that you can use for generating .onion addresses are eschalot for v2 addresses and mkp224o for v3 addresses.

Eschalot is a Tor hidden service name generator. It allows you to produce a (partially) customized vanity .onion address using a Kodi nox brute-force method. Eschalot is distributed in source form under the BSD license and should compile on any Unix or Linux system.

mkp224o is a vanity address generator for ed25519 .onion services that's available on GitHub with the CC0 1.0 Universal license. It generates vanity 56-character onion addresses.

The Promotion begins on August 31, 2021 at 12:00 a.m.  192.168.100.1 192.168.1.1 (start of day) Pacific Time ("PT"), ends on September 7, 2021 at 11:59 p.m. PT (the "Promotion Period").

If you aren’t already, you must be a follower of the Sponsor’s official Twitter account (@coinbase).

Your Twitter account must be set to “public”.

You can “unfollow” u/coinbase and set your Twitter account to “private” any time after the winner announcement.

Follow the directions in the prompt tweet (“Prompt Tweet”) from u/MrBeast (“MrBeast Twitter Account”) to be entered.

From your Twitter account and prior to the end of the Promotion Period, comment on the Prompt Tweet (“Entry Tweet” or “Entry”) along with the hashtag #CoinBeastSweepstakes which complies with the instructions specified in the Prompt Tweet and these Official Rules to receive one entry.

Interesting , they do that  constantley , I heard that their ceo is a close friend to the founder of ETH