I have had 20k for several years and the free bag carry on benefit would just show up when I added the flight to my account. Usually it would just match up automatically with my phone number and email that I give the agent.

Also one can book for other people: just need their name and birthdate.

I'll have 100k after my next trip because of the promo so we'll see how those perks get added.

If you see one of the other threads, the elite perks are only supposed to apply after you have gained status even though it doesn't say so on the website... When I achieved 50k, I couldn't book stretch seats ahead of time and that was the reason I was given. I'm just waiting to book trips after I reach 100k so I don't have to fight them for those benefits for any more flights than the 2 I already have booked for 2022.