On the sites I visit often I use uBlock Origin to make fonts large enough for me to read (damn you, presbyopia!). Otherwise I use Ctrl-+ to increase the font size (Daring Fireball, for example).

news.ycombinator.com##:style(font-size: 18pt !important)

myanimelist.net##:style(font-size: 14pt !important)

old.reddit.com##*:style(font-size: 17pt !important)