STEP Files huge when export

So, my issue is basically I was given a STEP file from a team member to finish up some cad, it was 116 mb from fusion 360. This was not a tiny thing, a huge project. So I just finished it up and now its 3 gigabytes? I added 5 parts onto it from a website and the STEP files combined together (of what i added) are less than 500mb. I’ve tried every single export option, and they are all huge. Some are even unloadable such as the Apple AR Format.

Another issue is that I cannot export to FBX and the Apple AR format combines certain parts together and some are not. Eg. the chassis was split into 2 parts, with some of it with the wheels and the other parts joined with the brain.

This is not the first time this is happening too.

Screenshot 2023-10-21 at 7.18.59 PM