I don’t know a direct solution.
Workaround
Draw a rectangle (frame) as large as the slide.
Select the color and line thickness of the line (border).
Click on the edge of the rectangle to mark it.
Click on Keep ratio
in the dialog.
And click on Protect position and size
.
Insert an image and drag it to overlap the slide.
Click on the image and select Arrange > Send to the back
in the context menu.
You should now see the slide size (frame) and slide content on the image.
First prepare a slide with the rectangle and then select in the menu
‘Slide > Duplicate slide’ as often as you need.
117391 HB Test Foliengröße.odp (237,0 KB)
Version: 25.2.0.3 (X86_64) / LibreOffice Community
Build ID: e1cf4a87eb02d755bce1a01209907ea5ddc8f069
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