When did chibiusa unlock her senshi powers in the 90s anime? Am I missing something?

Currently rewatching the 90s anime, I remember her transforming into sailor chibimoon in s2 of crystal but nothing as such happens in sailor moon R if I'm not wrong. I'm currently watching sailor moon S and chibiusa is back as a senshi, when did this happen? I'm assuming it happened off screen but is this ever addressed in the anime? How she unlocked her powers and stuff? Do I have to keep watching to find out or does the 90s anime leave that part out?