This can be done on a per-document basis without a background image by using a frame. Whether the result can be printed without an unprinted margin will depend on capabilities of the printer.
First, in Page Style..., set the margins on the Page tab and also set the color of of the margins on the Area tab. This will set the whole page background to the selected color.
Then, select Insert > Frame > Frame... and do the following:
- Click the Type tab and...
- In the Anchor section, select 'To paragraph'
- In the Size section:
- uncheck 'AutoSize' and 'Keep ratio' settings
- set both Width and Height to 100% relative to 'Paragraph area'
- In the Position section
- uncheck both boxes
- set both Horizontal and Vertical to 'Center' and 'Page text area'
In short, the resulting settings should look like this...

- Click the Wrap tab and set all Spacing values to 0.0.
- Click the Borders tab and click the leftmost Line Arrangement Preset to select no borders.
- Click the Area tab and set the color to white.
The page should now consist of a white document area and color margin.
Finally, put all of your document content into the frame.

Custom Colors > Document Backgroundand override that atFormat > Page (Alt+Shift+P) > Pageand deselectBackground covers margins, then go toArea(in the same window) and select a custom color (overrides setting in Custom Colors). Not that I would recommend this as Page formats are saved in the document and custom colors are saved in Writer. But if you need this, it is kinda possible. – yxz Apr 23 '23 at 12:28