Can a light with a built in motion sensor, be used with dimmer switch?
No, such an arrangement will either flat out not work, or have very poor reliability.

The motion detector logic requires full uninterrupted voltage and a dimmer switch is going to inject noise into the power which will disrupt the motion logic or its sensor.

Additionally, even if the motion sensor continued to work, the cycling of the light on and off would disrupt the load of the dimmer and make the voltage wildly vary.

You might get lucky with some quality components and dimmer settings, but it would be better to simply replace the bulbs with those of a lower wattage.