Help changing font size on my page!

How do I change the font sizes on my site, especially the Site Identity section and Id like the menu to be bigger https://www.cruzancowgirls.com/ Some of the font is barely readable at the default theme sizes. I don't really know anything about CSS coding, but I can try to do that if someone can help me  with it. Or is there an option to pay someone to do what I want for me?