Here's a quick tip for you:
When you use SharePoint Online's modern 'Document Viewer' web-part, you'll notice that regardless of window size the height of the viewer is unusually 'short'.You won't even get a full view of a single page in most cases!
We can easily remedy this with only the tiniest bit of effort!
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Then, click on 'Embed Information'.
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Its sacrifice will not be in vain, however, since we will be taking the handy little embed code it gave us to use in a new Embed web part.
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Paste the embed code into the Embed web part settings pane.
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As you can see highlighted above, we're going to change the embed code's default height value (which for me was a measly 677 pixels).
I chose a more suitable value of '1120px', but you are welcome to toy around with it until it displays your document just right.
In the end, you'll be welcomed with a much more useful display of your document!
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