Basic UI Settings e.g. Font Size

[Bader]

You can do that by editing your graph/logseq/custom.css file.
To change the font size and line height (change the values):

:root {
  --ct-text-size: 18px;
  --ct-line-height: 1.6;
}

You can also change the font used if you prefer something else:

:root {
  --ct-text-size: 18px;
  --ct-line-height: 1.6;
  --ls-font-family: "JetBrains Mono";
  --ct-page-title-font-family: var(--ls-font-family);
  --ct-code-font-family: "JetBrains Mono";
}