Neocities does support fonts
Although firstly I assume you need to be a supporter to upload them (you can still link them form other hosts like ichi.city)How to:
Its really simple, you just need a ttf file (the standard font file you get from most font sites) and then I like to make a font.css file to make adding the font to a page simple. Iv attached both below as examples (basiic font made by cinni!!)
Then to add it to your webpage just link the css and set your font.
<link href="basiic.css" rel="stylesheet" type="text/css" media="all" />
font-family: "basiic", monospace;
To adapt this to other fonts, just change the ttf file and edit the css file so it has the right names ^^Hope that helps!
(Also for non neocities hosted or other kinds of web fonts, Iv never used them, but the process would be the same!)