How do I know what type Of gas my new car takes?

NEW CARS have NEW MANUALS and STICKERS on the GAS FLAP! READ THEM and SEE! 

Regular works fine in all cars made domestically.  If it comes out of a pump, it goes in your car. Oil companies kept it simple.

just read the owners book you idiot .. or call the car yard and ask , but they will tell you to read  the  book fool ...

The simple answer is to read the owner's manual or look where the fuel fill is.  I do believe they write the fuel type there.

I'm sure the Bronco came with an owner's manual. The information is in there.

You read the damn owners manual.

Fresh water should do. DiSeal ffs, is that some sort of mastic to stop your toilet leaking?

Try reading your owners' manual.  

the easiest way to find out is push the little microphone on your Google search and say what kind of gas does my 2021 Ford broncos sport use?

The new Broncos don't come in diesel. So do not fill it with diesel.

 Check the owner's manual,  regular gas is fine.  The mid-grade and premium octanes really only need to be used when your engine starts knocking.  The federal trade commission had a study that showed no evidence of increased gas mileage or better performance by increasing the octane.