Is there a standard keyboard only method of removing focus from all HTML form inputs?

When navigating an HTML form using Tab, a properly designed form will allow that all interactive elements are accessible and focusable, but how does one break out of the focus using the keyboard?

Using a mouse click somewhere dead on the page, such as in between interactive elements, will achieve the removal of focus (blur) from whatever element had it, but can this be achieved with a keyboard combination?

I have tried every reasonable (to me) combination of keys while a form input has focus, but other than unintentionally doing all kinds of other things, I've found no way to simply stop focussing on the input.

I have searched the internet via Google, using multiple queries and can find no simple instructions regarding the actual keys to use to operate forms with a keyboard. I haven't even found documentation about how to select a radio option, or check a checkbox, and learned that by trial and error many years ago.

I feel it reasonable to assume that a modern web browser, built in line with standards, when presenting an HTML form, that has not been improperly designed or manipulated by JavaScript or CSS in any way that affects its operability, should allow simple navigation by Tab, and also, and importantly, allow that navigation to be terminated without requiring a mouse, but how?