2022 Bronco base wheel options...

Yes, you can put 17" or 18" wheels on a Base. Same suspension as on the BB, BD, OBX.
As for the widest tire on a 16" wheel (aftermarket as you say), that depends on the width of the wheel you choose.

You can put any diameter wheel you want. The issues start to arise with width and offset. If you want to stay within factory specs look for a 7.5" - 8" width with a +30 - +55mm offset. If you start going wider you risk hitting the suspension without some sort of lift or level. Typically a 285 width, which is 11.2" wide is as wide as you want to go on a 7.5" wheel. Tire manufacturers give the range of what wheel width is recommended for a specific width of tire. Many people have put 285/70-17 tires on stock 7.5" wheels. Some say the crash bars need to be removed. Others do not. It really depends on the tire. You could also go with a 285/65-18 or a 285/75-16.

You really need to decide if you want to go with a wider tire or a tall skinny pizza cutter tire first. Then you can start deciding on wheel size and then exact tire size.