As mentioned in another comment, Windows Sonic is the default spatial implementation provided with Windows by default. There are also paid Dolby Atmos and DTS plugins available through the Microsoft Store where licenses may be included dependent on your hardware or OEM, e.g. my Logitech Gaming Pro X includes a license for the DTS plugin.

Personally I do like the Dolby Atmos plugin, I have my computer connected to a TV with sound passed via eARC to my soundbar. However, if you're consuming Film/TV with such a setup, you probably just want to enable Dolby/DTS passthrough instead.

Possibly, but that might also be a windows/device thing because Dolby Atmos tracks I listen to on my Apple Music/iPhone sound _Amazing_

I believe that's Windows Sonic for Headphones.

This enabled itself after an update a few years ago and I thought my headphones had broken.

I think it's the company that shits on the cinema movie viewing experience by spamming before every movie.