I upped the font size on my Pixel recently and this is one of those sites where (in Firefox) the sidebar takes up more than 50% of the width of the screen and retains tiny text while the article itself wraps on a couple words per line.
You're right. I've used reader mode(the paper in the url bar in Firefox) to solve this.
1. Invest in your senses
I see you noticing a thing, with your senses. Sincerely:
A (used) folding phone offers 66% body content, 33% sidebar. Is a noticeable improvement.
Reader mode works. Just tested on Firefox on a pixel...
"Accept everything"
In the sprit of the article, "grant me the serenity to accept the things I cannot change, the courage to change the things I can, and the wisdom to know the difference."
Mentioning these things in a comment is neither accepting of how it is nor changing it. You can't change the site - the author died. You can change your browser or reading mode or whatever. Or you can just accept it is the way it is.