I’ve never had Premium membership.
Back in the day, there were no paid Premium membership options, it was all entirely free and everyone had the larger sized avatar as standard. Then the paid-for Premium memberships were launched, and the larger sized avatar became only available to Premium members, and a new smaller sized avatar was made standard for free membership. Free membership could carry on with the larger size avatar, until such time when they changed their avatar, then they had to downsize. That’s why I have the larger size, because I’ve never changed it.
IIRC, when everything was free, there were feature options, but everything was paid for with some kind of points system. You accumulated points by posting and starting threads etc. One option was to customise the line under your username, but not only your username, you could change the same line under other members usernames too, which was a bit of fun. Like you could change it to ‘Maria’s #1 Hater’ and that member had to stick with it for about a month, or could change it back if they paid enough points. Something like that..