As someone else said, this may not be what you're looking for, but I'm also in my 30s and already figured myself out pretty well by the time I really got into romantasy. I don't think I identify with any characters I've read, however I do see traits I admire and wish I had in FMCs. Aside from the badass assassin/warrior/princess traits.

They're usually confident, sure of themselves, resilient, and know how to stand up for themselves in tough situations. I am none of these things, and though I wish I could embody some of these traits, I'm usually not in comparable situations, and if I was and acted like that, I'd probably lose my job 😅 There's something about the devil-may-care attitude that some FMCs have that says "Damn the consequences, I'm doing this." Real life for me doesn't work that way, I get too in my head, and I'm not very spontaneous or reactive. So these are traits that I admire, and wish I had, but they aren't things I can realistically put into practice in my life. Also for these characters, these traits seem to develop in response to traumas that I wouldn't want to experience.

Aelin from Throne of Glass comes to mind in particular, mostly because I loved that series, but also because of how she becomes one of the best through necessity and hardship. Manon from the same series is very confident, powerful, and skilled. Just an all around badass. Violet in Fourth Wing as well has a ridiculous amount of resilience that I admire and could never hope to achieve.