Ther are 3 types of fractional HP motors that are common, Start switch with a start winding, Shaded pole, Capacitor run motors( these can also have start switches.)
The problem slowing down a fractional motor with a start switch is that if you slow them down very much the start switch kicks back in and that will then burn the windings or blow out the start cap if it has one. If you hear them click when they start they have a start switch.
Cieling fans are normally a shaded pole motor, the do not have a start winding that is feed buy the power supply, the can be controlled using resistive or transformer switching or a rheostat.
The tag does show a microfarad symbol so these motors are probably cap run motors. these can be slowed down about 35% by droping the voltage. You can slow them further by VFD droping the voltage and frequency. If you don't drop the voltage as the frequency comes down it will blow out the capacitors as well as heat the windings.
I hope this helps