Don't know if you'd call her badass but the female lead in Koi dano Ai dano is great. Honestly, I can't really think of many badass female leads in the "shoujo" genre.
La Dolce Vita di Adelaide
The rest I'm gonna list here aren't "shoujo" but they do feature good female mc's and some do give off vibes that I'd argue are shoujo in nature even if they don't list the manga as shoujo.
The Pharmacist's Soliloquies
Koushaku Reijou no Tashinami. One of the few really good "otome" isekais.
Superior and its continuation Superior Cross.
Teppu has a pretty badass female lead but it's not shoujo or romance and has some ridiculous drama (well it tried) they clearly intended to setup this whole thing and flesh out the story but it sort of just ended after the first arc, it was probably axed.
Shut Hell has a really strong female lead as well.
Just discovered Inso's Law, I know it's not what you're looking for but I'm hooked on the story and premise.
This Girl's a little Wild. She is badass but after the first half of the season, it was pretty much just her being cute with the male lead.
Reminiscence Adonis. Now that is a true badass female lead, no bullshit.
