Hello OP, I understand how you feel. I have 2 sons now in their 20's. The transition from child to adult in one day isn't especially logical. It is quite arbitrary, but it has to be. As a society we've picked a point at which people can be considered adults and your DD has passed it.
Your DD is now legally an adult and can lawfully go to venues that serve booze and stay open late, amongst other things. That's the law of the land and rightly it offers her the same liberties we all enjoy.
As such, it is unreasonable to curfew her. You can't. Really.
However, with rights come responsibilities. It's not unreasonable for you to set ground rules in your home, such as being told if she plans to be out late or if her plans change to be made aware. It's not unreasonable for her to stay out late but it is reasonable for you to expect her to avoid waking anyone else on return, for example. Ultimately, she can do as she wishes as long as it doesn't disrupt or disadvantage anyone else. It's reasonable for you to hold her to that.
I don't know if your DD is in education or work, but it's also reasonable for you to set some rules around expectations regarding that. Is she paying board? If not, does she receive an allowance from you? I could afford not to charge board but I made them pay into a fund that they could take once they left home. Does your DD contribute to maintaining the home in time and effort? As adults we all have to chip in a bit when it comes to cleaning, decorating and so on.
In the end, you want her to thrive, and she can't do that if she's being treated as a child under your roof with curfews etc. She is also unlikely to thrive if she's permitted to set all her own rules - as adults may - but kept financially and domestically like a child. I think this is one of the toughest parts of parenting and easiest to get wrong. Ultimately you must still set boundaries, and they must be revised as circumstances change, but you must respect her autonomy. She can't learn to get it right if she isn't given room to make mistakes.
She will leave home one day, all being well. And whether she shares a place with house mates or colleagues, has her own family, neighbours, lives alone in 20 acres of woodland, whatever... She'll be fine if she has good guidance.
It's hard to loosen the grip but it is important to do so. Congratulations on your DD becoming a woman. Good luck, OP.