A lot of Discord servers use that pattern, and it seems like it’s born out of forcing all custom features through chat bots?
In Discourse this would be really easy if we had a tl1 requires likes given setting (we have it for trust level 2). You could restrict all categories other than a “rules category” with a single “rules topic” to TL1… and to gain access to TL1 and all other categories users would have to like the rules topic.
Maybe you can shift all your trust level settings to make this workable so everyone who agreed is trust level 2 (using tl2 requires likes given)?
Without a new setting or more dramatic trust level setting changes, you could also use existing trust level settings to do this based on time rather than an explicit button click. You could have 1 category and topic available to tl0, and you could change these settings:
tl1 requires topics entered: 1
tl1 requires read posts: 10 (maybe you have 10 rules split out across 10 posts)
tl1 requires time spent mins 3 (to force people to spend more than 0 time reading)
So then if someone read all 10 posts in your rules topic and spent a few minutes there, they’d gain access to everything else.