Probably but reading something online is different to print

It is, but it doesn't look good in that size on a screen. Increasing the font size would help enormously.

Isn't the default latex font still Computer Modern? This is Latin Modern which derives from CM.

I mean it depends. Xelatex and Lualatex, which are actively maintained, use Latin Modern. If you just use pdflatex then yes it's Computer Modern that gets used.

The typefaces are close enough though that it is quite difficult to notice the difference.