Last time I was on vacation alone I googled the few things I knew I wanted to see/do, and the rest of the time I just went out and see where I end up. Looking where locals go and do that is also a great trick.
My experience is that most easily online findable things are very tourist-y. I preffer to see more of the non-tourist stuff. Knowing a local is then the best, but by lack there off, just go with the flow.
I can only say Coca Cola taste the same in The Netherlands, Germany, and Vietnam. While I can generally tell quite well when I get a different cola then a Coca Cola one. Based on that there should be some kind of international standard?
I can imagine US being different due to less strict rules around food than EU (much American junkfood is altered in the EU market due to this). But then I'm suprised Vietnam taste the same for that same reason 🤔.