On this page:
As Cross-platform source code: Simple cross-platform (Win/macOS/Linux) host application allowing you to open the editor of a VST 3 plug-in (with HiDPI support on Windows/macOS). Call it from the command line:
On Windows and macOS you can also drag and drop a VST 3 plug-in on the executable via Explorer/Finder.
Check the folder "public.sdk/samples/vst-hosting/editorhost" of the SDK!