Alex, would SO hot be ТАК жарко?

Yes

..wanted to avoid “very”

Good thinking. Me too)))

But I think SO is something different.

I can remove the translation, no problem. I just thought that “really” is also not the same as “very.” I imagined someone say this when going out of the house or answering a question about their vacation etc.

REALLY and VERY mean the same thing, have the same intensity. In English, they’re not the same as SO. Maybe in Russian ОЧЕНЬ and ТАК have the same meaning?

As separate words - no, just like in English. Both “really” and “so” add some emotion, while “very” sounds neutral, just as a degree of heat. I’m deleting my translation ))