No, just that's where they are. The law says a US citizen who happens to be in Berlin (maybe on vacation) is subject to German law. Fine says GDPR, I'm EU law, so I apply to that US citizen too.

That's how most of the law works. If I commit a felony while on vacation, I'm subject to the penal code of the country I'm visiting, not the one where I have residence.

There are more scenarios.

I am US citizen I have residency in US and I make new account (make contract) with company providing service that is based in US with rules as in US. I visit Berlin for a week and I log in into account to use the service. Is that falling under GDPR?

I am US citizen I have residency in US and I go to Berlin where I make new account (make contract) with company providing service. Now I go back to US and login to use service. Is this one also falling under GDPR?

Which law is applicable to contracts between two parties going into contract? Usually in formal contracts you have place and date. I assume you agree on laws of place where contract is made. So if you are at the moment in Germany that is the place of making contract.

I think also criminal law and civil law are quite different in many ways so I would not draw conclusions based on how commiting felony is handled.

That's simplistic. If you kill a Dutch in Berlin, you can be prosecuted by Germany, NL and your own country.

The gdpr only applies to EU residents. People here on tourist visas are visitors not residents.

No, physically present within EU jurisdiction

Residency not required, I’ve heard.