Margins in MS Word 2021

I have recently set up a new Windows 11 machine and added Office 2021. Things are fine but in older versions when I set the view options to "Show Text Boundaries" I used to get a box showing the margins which filled the whole page, clearly showing the boundaries for the whole page even when I had not added any text yet. Now I only get a small, single-line, oblong box at the start of the document which expands as I type. If I start a new paragraph it creates another of these boxes which gradually make the document look very cluttered as I go on.

I have sought high and low to find a way of viewing the margins as I used to in older versions of Word but I cannot discover how to do that. If this new behavior is by design then I have to say I am not enamored of it. Maybe I am missing something?