can you recommend any J drama where the female isn’t overly submissive but is strong?

Hi!

Did you give a try to "Uchi no musume wa kareshi ga dekinai", which is currently airing?
https://mydramalist.com/74999-uchi-no-musume-wa-kareshi-ga-dekinai

The main theme is love between a mother and her daughter, but both of them are also looking for love. The mother is a writer and is really strong. The daughter also has her own original personality.

It's cute and funny!

One of my favorite female leads is the one from Buzzer Beat. I don't know about strong, but I think she is well rounded, not submissive or cutesy, and grounded. 

I have not seen many jdrama yet, but I liked Ashi Girl. 

Good rom-com (a bit crazy) with scifi elements, mostly set in Sengoku period. FL travels back in time and tries to protect her beloved prince. 

my recommendation is 7 Secretaries

I would recommend jdrama Lupin no Musume (2019) - it is good balance of comedy, action, crime, drama and romance. If you would take stories about James Bond, Mission impossible, Romeo & Juliet plus some others and mix them together then you would get this. :-D It is really funny show.

FL (daughter of thieves) is strong and dates ML (police officer). :)

The Confidence Man JP - doubt there is any romance in it, tis hilarious though. Very funny.

Hanazakari no Kimitachi e - Romance of a sort.

Minami-kun no Koibito - My Little Lover - Very cute

 Nee Sensei, Shiranai no? - Not your usual romance.

Raise de wa chanto shimasu

W no higeki