If you have a recent install you settings.js should have a section at the bottom like
/** Select the text editor component used by the editor.
* Defaults to "ace", but can be set to "ace" or "monaco"
/** The follow options only apply if the editor is set to "monaco"
* theme - must match the file name of a theme in
* e.g. "tomorrow-night", "upstream-sunburst", "github", "my-theme"
/** other overrides can be set e.g. fontSize, fontFamily, fontLigatures etc.
* for the full list, see https://microsoft.github.io/monaco-editor/api/interfaces/monaco.editor.istandaloneeditorconstructionoptions.ht>
//fontFamily: "Cascadia Code, Fira Code, Consolas, 'Courier New', monospace",
just make sure you switch ace to monaco to enable that editor then edit (remove //) from the fontSize option