Age of backpackers in SEA and party hostels at age 28

I am going to SEA (Thailand, Vietnam, Loas and Cambodia) solo in June for 10ish weeks. I am 28 and one of my main concerns is that when I check into a hostel I will be surrounded by 18/19 year olds. I have no problem chatting to them and hanging out with that age group but I do want to meet people my own age too.

I do also want to go out drinking and experience a few party hostels. I did an interrail trip this summer and found some of my best friends and the easiest way to meet people was staying in party hostels. I did a mix of party hostels and chill hostels/private rooms just so I can have a balance, I was happy to drink loads one place and chill at the next. This ideally would what I will do in SEA

I am just worried from posts that I have seen that at party hostels in SEA I will be the oldest one. Would love to hear folks experiences in SEA and the age range of travellers at these hostels or just in general at various places.

Any hostel reccomendations would be great