XF 1.5 How do I change the font size??

I'm assuming you're referring to the title itself.

Typically Style Properties -> General -> Page Title
Thanks ever so much @Russ ! If your not to busy, I have an additional question.
If I wanted to have my node tree like this

Category Title [catergory]
General [forum]
Next category Title [catergory] [no subs]
General 2 [forum]

is it possible to make it so that the second category ISNT a link / clickable?
Sorry if that doesn't make much sense.
this is what I'm trying to achieve.