My dd (6) is pretty bossy too. Basically when it comes to playing and spending time with her we do things that allow her to be the boss. She's been making "wilderness stew" for years (the term is from a Berenstain Bear book). I get out all of the bits and things in the back of the cupboards that I don't think I'll ever use (molasses, flour at the bottom of the bag, stale oats, etc) along with the food coloring and let her go to town. She still loves doing it, although now she's moved on "cooking" with things she collects from outside, leaves and flowers and things. We make "wraps" with dirt and whatnot in leaves, then actually fry them in a frying pan.
The other thing we do alot is pretend. In our case, my hands are two birds named Cheep and Chirp. Sometimes she is like an older sister, sometimes like a teacher, sometimes like a mom. No matter what, she bosses them around alot. She'll put makeup and wigs on them too, and spend hours making "props" little houses, chairs, dishes, etc to be used in our games. To be honest, I don't really enjoy pretend but the game is so good for her in every way I end up enjoying it anyway. Sometimes I even use it to "talk" about issues in her life, like if I know that she had a bad day at school I'll have Cheep and Chirp ask her about school and then discuss it with her (although since they are "younger" than her they always ask her about what should be done, they NEVER give advice
). They're like bratty little kids and funny. We've been playing this game probably since she was 3 and it's still her FAVORITE.
Anyway, of course you can't do the exact same thing (your dd would probably look at you like you have 3 heads if you tried to tell her your hands are birds) but the basic concept is just a game where she is boss and it's funny. Maybe have her be the librarian and have some stuffed animals or hand puppets be the children she is reading to. Then you make the stuffed animals talk and have personalities, ask funny childlike questions that she has to answer.