List of random practical tips that have popped into my head regarding copenhagen:
Check the weather before you go, temps canbe anywhere from the first cpg where it snowed to the 20+ we had last year. dmi.dk is the official danish weather forecast and usually pretty acurate. BRING A RAINCOAT no matter what it says. Danish weather sucks and rain is usually combined with wind that makes unrellas pointless.
For navigating the city including public transport google maps is totally fine. You can use the app called Rejseplanen if you want to but generally google maps works just fine.
Get the app DOT Tickets on your phone and set it up before you go if you plan on using public transport. Buying tickets on your phone is waaay easier than having to deal with physical paper tickets. Denmark does have their own version of the oyster card but its pretty much exclusively for danish residents so if you dont have one already youre kinda shit out of luck on that one.
Dont buy alcohol that the venue if you can avoid it. Shits crazy expensive already and at the venue its pretty bad. Buy that shit in supermarkets instead (im not telling you to sneak it in but hey i didnt see anything). 16 yearolds are allowed to drink anything thats like 15% and under, 18+ for everything else.
PLEASE go spend some time in actual Copenhagen. City is fucking great and it would be a shame to miss it.
Do a bit of research beforehand if youre into food at all cause Copenhagen has some really good food if you know where to look (go to gasoline grill). Expect it to be on the expensive side though so if you dont wanna have things be crazy expensive all the time you should cook for yourself in any way possible.
If theres interest in actual sightseeing and stuff youre welcome to msg me on discord wan#5251 or someone else idfk
EDIT:
This travel guide is really well made and well worth the watch. Just dont expect to cycle around in copenhagen. The headache of learning all the rules etc and not pissing people off/being a danger to those around you is simply not worth it imo.