I've had many decals on my cart over the past ten years. I've peeled them off when tired of them and added new ones. I bought all of them on eBay, currently under a general search I found 300,000 different ones. You can narrow your search by team, city, state, flag, whatever you're looking for. Make sure it's sticky on the back and not the front, a few are made to go inside the window and have sticky fronts, not many. I've gotten my license plates on eBay also, I have a Lightning plate on the front and a Blue Lives Matter flag plate on the back.
Here's a general search link.
https://www.ebay.com/sch/i.html?_fro...cals&_osacat=0
Here's a narrow search for Baltimore Ravens decals/stickers. This will show how many choices there are for just one search item, it's a lot.
https://www.ebay.com/sch/i.html?_fro...vens&_osacat=0
Currently on my cart I have just the Tampa Bay Lightning on the front and American flags on the sides. The round Lightning decal is 12", that's a good size.
https://scontent-atl3-1.xx.fbcdn.net...1e&oe=616EB079