2021 450 to plastics compatibility.

I doubt it, two different machines.

You can go to a online parts store such as Partzilla and pull up a diagram of each one and compare.

I forgot to mention I have a 2021 450 WPS and the plastic I would be looking to swap out would be off a 2022 Kodiak 450. Based on what I saw on partszillla, they look the same.

There were no model changes done to the 450 Kodiak between 20 and 21. Therefore the plastics would be identical other than color options. There should be zero issues.

A quick check on partzilla shows the fenders from a 2021 450 fitting everything from a 2020 right to a 2023. So zero issue

I was thinking that they were wondering if the 700 plastics would fit on the 450. My err.

700 to 450 no as there are differences, 450 to 450 yes. The ESP is just power steering. I have a base Kodiak 450 and my wife has the 450 SE with ESP and the plastic is the same on both, just different colors and some decals.