My domain is on Google since ~2006, the name changed a few times (Google Apps initially, now I think this is G Suite) and I benefit from the free grandfathering program.
I wanted to try the new 2018 Gmail interface but it did not show on my account in settings.
I found a Google support post which suggests that this new interface should be enabled on the domain console (in "Enable Gmail for a domain or organizational unit"):
In User settings, scroll to New Gmail Early Adopter Program.
I do not have this New Gmail Early Adopter Program entry (there are three available: themes, delegation and name format).
Will this new Gmail interface be made available to "old" G Suite domains?