Without knowing too much about what you like, , here's some recommendations:
Criteria:
+Woman protagonist
+Fantasy (or isekai trash)
+Agency (has their own goals and objectives, may or may not be moral)
-Fan Service
-Romance (I get the feeling you just want to see the female lead kick ass, and not have to deal with romantic entanglements, but let me know if I'm off)
-Gender bender ( not sure how you would feel about this, there's stories that technically fill the afore mentioned criteria but it's a guy forced into a woman's body.)
I was iffy on otome villainess manga as well, but if you like those I have a couple ideas. Obviously I don't know what you've read before, sorry in advance if you see something you've read
Frieren at the Funeral (Sousou no Frieren)
More of a spiritual journey than action. Elf woman defeats the demon king with her party, she grows distant with them and only returns at the Hero's funeral. She regrets letting their relationship go fallow and retraces her steps in order to learn who they were and forms new connections along the way. More platonic love than romantic, but you discover along with her how much she loved her former party and cherished their time together, even if she couldn't express it at the time. Slow, contemplative, and very thoughtful. don't get a lot of manga like that period, much less for FLs.
A Tale of a Small Town hardship in Sengoku Era - An Agriculture Comic (Sengoku Komachi Kuroutan: Noukou Giga)
Time travel counts as fantasy right? Teenage girl attending a agriculture highschool gets spirited away to the Sengoku period. Stuck centuries in the past with no clear way to get home, she struggles to survive in the warring states era, torn between returning to her family and saving the lives in front of her. Follows a lot of isekai kingdom building tropes (almost encyclopedia knowledge of everything having to do with farming and a little chemistry and medicine because why not), but the Fl is in my opinion endearing enough to go along with.
White Blood
More magical realism than fantasy, but, vampires. More action oriented (with superb art) the the last two. Angsty vampire girl goes on mission for revenge. I sort of broke my rule with the romance, but it's as much a romance as any Shonen with a male protagonist, and there are as many fist fights as well.
Guardian of the Sacred Spirit
Short but sweet, Martial artist Balsa escorts chosen one on his way to become the Fairy Guardian, Balsa fighting her way through monsters and men. Also has light novels if you're into that, and an anime I think.
Don't want to inundate you, so if you'd like more, don't hesitate to dm me. (open invitation to anybody reading this). It's fun to do.
Honorable mentions:
STRAVAGANZA The Queen in the Iron Mask: A lot of fanservice, but otherwise a cool read about a swash buckling queen in a sword and sorcery universe. Also, love the artist in general.
Baikoku Kikan: Personally yet to read this, but is from the author of Youjo Senki, so if you like alternate history, you're golden.
Shut Hell: TECHNICALLY a gender bender, it's more like two souls possessing the same body. A good read.
And for sci fi:
Queen Millennia
Silent Mobius
And for a curveball:
Raqiya: I won't spoil it, but read until the end.
@Krune
New hero for Mynoghra, I think it's at some point in the next arc if you're reading the manga. As for Her Majesty...
She can only have one hero unit but there's a process to turn other races into psuedo swarm with special traits, which she'll do a few times in the future...which kind of negates the need to genocide whole other kingdoms if you can just literally absorb them, but whatever, don't think about.
Frieren: Already reading, love it.
Kuroutan: Already reading, love it even more.
White Blood: Already reading.
Guardian of the Sacred Spirit: Read both mangas already.
STRAVAGANZA: Not a fan of fanservice, so I passed over it before.
Baikoku Kikan: While I enjoy Youjo Senki, this one feels more serious. Didn't know it had a female MC though.
Shut Hell: Not my cup of tea.
Queen Millennia, Silent Mobius: Too old.
Raqiya: Not my cup of tea, but I know someone who'll probably like this one a lot.
yeah this is probably the only way this could go. Making all the humans and angels be deranged monsters, a sort of inversion of the concept of beauty. Would've worked out better if the MC weren't a stereotypically beautiful young woman; were she the ugliest monster on the outside but close enough
Plot twist that is unlikely to happen: the angle falls in love with the knight swarm and asks the MC if she can have the knight’s hand in marriage. MC unsure of what to do says that it is the knights choice and so begins the sub plot of a battle maniac angle trying to seduced the blood knight.
@Lost-Happiness lol I didn't think about that, you're right haha, but in curious, also maybe this existed in the game so it might be interesting haha~!!