Sort of. CO2 wise it's worse burning. But free floating plastic creates problems from toxic addivites causing hormonal problems, and from the microplastics (which all plastic degrades to in the ocean eventually) clogging the stomachs of krill etc.
Burning the plastic in a properly fitted plant largely "cleans" the toxic additives by burning them too.
Plastic in nature will eventually turn into CO2, just slower and with a lot of bad side-effects.
"Recycling" the plastic has been shown to instead be sold to whatever-place-du-jour which ignores laws. Often it's burned in open pits, creating both immediate CO2 release, as well as new toxins created in the imperfect burning, and leaching of the old toxins, as well as large chunks of unburnt plastic floating in the wind.
And burning plastic is a waste, but a lesser waste, because it's turned into some electricity.
Upholding recycling structures for plastic also creates a false sense of "this is fine". Instead, it should be treated as low-level-dangerous refuse which should be burnt and only used for applications where this trade-off is acceptable.
