Yes to both.. Will be a possible rule for you if you got Submission at 6 or higher, will be a possible rule you can give to your sub if you got Dominance at 6 or higher..
Please don't hate me
I have attained a sub and a Dominance (I got the dominance rather than assertiveness from the library but I have not finished the library story yet, working on it) of higher than 6. But it is not appearing as a possible rule unless there is another prerequisite.
I did buy a chastity cage matching my sub's parts as well just to check
I don't have a master (yet) but I did give a rule to my Sub and I was given the option to collar them, which I did
For most of the time I didn't have a rule set but this does also extend to previous playthroughs when I did give subs rules and I never saw an option for chastity ever. It's why I assumed it just wasn't in the game
And I've had this issue across devices. Before I used to play on Mac but then switched over to windows (But I did not always pursue the library storyline either to turn assertiveness and compliance into dominance and submission so that may be messing with my memories)