Methods of changing font size and style on Vantage theme

Hi, I use the free version of Vantage and would like to increase the size of the font for text.

If possible I would also like to change the font styles.

I’ve read that it is possible to change the font and style on the free version using CSS (something I’m not familiar with). But it seems that this CSS needs to be refreshed each time the theme is updated – is that correct?

Does the premium version of Vantage allow for the font size and style to be changed and if so is there any documentation / videos / examples to show what can be done, so I can see the potential results before purchasing?

Thanks for your help.