First, go to
https://<yourname>.sanity.studio (or to the url of your studio if it's hosted elsewhere). Then open the developer console (usually by one of the keyboard shortcuts
Control+Shift+I depending on what browser/platform you are using)
- Open the Sources tab
- Find the
app.bundle.jsfile in the sidebar tree view.
- Hit the pretty print source button
- Locate your schema types by searching (e.g. try searching for one of your custom types) it in the source view.