I personally studied ballet for a while, but I can't learn it now ... Then I danced belly dance in the gym, which felt very good and slim, but some soft and tough movements were a bit difficult to master and needed more practice (but many aunts aged 4 or 50 danced in the fitness center, so you can let go and don't worry so much, they didn't learn as well as young people ...)
Hip-hop is also good. Depends on your personality. Dance some dynamic dances if you are lively, and dance ethnic dances if you are introverted.
I suggest you go to leg press every day, get off the bridge, practice flexibility, or do yoga. Because no matter what kind of dance, a little more flexibility is good, which will also make your figure more beautiful.