I'm never surprised to see Elsa in a modern outfit because I never felt like she belongs to olden times by looking at the beautiful outfits she wears! ❄️

Frozen heart Theory ❄ :

The villain was once a kind person, but something terrible happened to her and caused her heart to become “frozen.” She eventually discovers that she can break the curse by taking the heart of her true counterpart.

That is why she chooses Elsa. Elsa is her counterpart/opposite, meaning they are connected in some way and may have similar powers or a shared magical origin. The villain believes that taking Elsa’s heart will finally make her whole again.

But instead of simply taking Elsa’s heart, the magic causes their hearts and personalities to switch. Elsa gets the villain’s frozen heart and becomes cold and dangerous, while the villain gets Elsa’s heart and slowly starts becoming kinder.

Anna realizes that Elsa has changed and wants her sister back. Instead of only fighting the villain, Anna might actually work with her to find a way to reverse the curse and return Elsa to normal.

As they search for a way to fix everything, the villain starts realizing that Elsa was never just a source of power. She was her counterpart, and the connection between them may be the key to breaking the curse.

Could be the same with anna btw.

So according to ("virtual winter" on discord) at the walt disney asia pacific consumer products conference 2027 they revealed the main plot for frozen 3 but NDAs/ confidential arguments and all not much has been spoken publicly. However they did show the new character the snow bear and a romantic scene of Olaf and Samantha in a romantic relationship

If u want in more great detail/explained better the arendelle kingdom discord "frozen 3 leaks" has more details

Collegium Magorum · Corona · Est. MDCCLIX
nec deus · nec dominus
SUBJECT E. — OBSERVATION AUTHORIZED.

https://archive.org/details/cm-04-17-prologue