Does Tiamat rule over lesser devils?


I am in a situation where the Cult of the Dragon is in direct conversation with a bearded devil that wishes to wreak havoc on their camp. (It’s a long story that I’m happy to provide details with if asked)

However, my question is this: Although Tiamat is no longer an archdevil and only resides within Avernus of the Nine Hells, does she have any control in this situation to tell the bearded devil to step off? I have my own thoughts, but I’m curious to start a discussion on it.