>Right, same as a police officer who asks if they can "look around" or "ask a few questions". ...But in general you'd be a fool to do so, and you also may say "no"
This is not only a very naive take, its a dangerous one - people have been killed by law enforcement for doing what you are suggesting. Law Enforcement Officers in the US has what is known as qualified immunity. In practice qualified immunity means as long as the LEO says they believed they were following rules (even if they were not), then they can do anything they want to you (including kill you) with little to no personal consequences.
In other words, you can say "No officer, you can't look around without a warrant", to which they can say "I see an object that may be a gun, and you're moving your hand in the direction of your pocket. Stop. I'm afraid for my life, I need to break your car windows and throw you on the street"
It's common enough that a LEO can publicly and slowly strangle George Floyd on the street, recorded and in front of others, and the only notable/unusual aspect is that the police officer was convicted of a crime.
Your rights don't mean shit to cops.