Some types of plastic can be cut with a hot knife.
However cutting plastic with a hot knife will emit fumes and plastic smell which could be harmful to breath in so it's best to have ventilation when cutting plastic with a hot knife.
A grinder or even just an electric saw can easily cut plastic as well.
A hack saw will also work great to easily cut the plastic.
But if you have a hot knife then the electric hot knife should easily cut through the plastic.
I've cut plastic with my hot knife before and it worked great but for thicker plastic a saw will work much better.
Breathing in plastic fumes and smoke is not good for your health so it would be a good idea to wear a mask as well when cutting plastic with the hot knife.
That will help filter the air you breathe in so that you don't breathe those nasty fumes in.