Menu Bar Toggle

Right-click the bar

When the bar is set to hide, move the pointer to the top of the screen so it slides in, then right-click an empty part of it to make it stay. Right-click again to hide it.

Status icons and open menus are left alone, so nothing else changes.

A keyboard shortcut that won't clash

⌃⌥⌘M out of the box, or record your own. Before it's accepted it's checked against macOS's own shortcuts, the ones you've made in the Shortcuts app, and other apps' global hotkeys — and if something already has it, you're told what, by name.

Per-app rules

Hide the bar whenever a particular app is in front — a remote desktop session, a game, a video player, a presentation. It flips as you switch apps and puts your usual setting back when you leave.

Pick from the apps you've used recently, from what's running, or choose any app.

Seven icon styles

One small icon in the status bar, in the style you like. Every style has two glyphs, so a glance tells you whether the bar is currently set to hide.