Thank you!
I ran the help for createrawtransaction and I see what you're saying about the sequence field. I also see it references locktime and replaceable fields. Replaceable seems like it would need to be set to True to turn on RBF, correct?

For the sequence number, it can be anything as long as it's lower than 4294967293? (and lol where does that number come from? Now I am curious AF)