I’ve downloaded a PDF manual in several languages.
The English section is the last 17, I have opened the full PDF in Draw, and deleted the earlier pages, except for the cover page.
That done, it has been Exported Directly as the English PDF Manual; sadly the page layouts have been altered in the process.
How do I achieve my desired aim?
Just realised that the original when opened in Libre Office Draw, every page is similarly skewed.
Make sure that you have installed all the fonts used in the pdf.
If you click in some text and the font name is shown in italics then a substitute font is being used which might have different metrics to the original font.
Oh dear!
I don’t generally do much text work so don’t have much experience with Libre Office in any form.
Clicking anywhere in the PDF display just creates a blue box around the text.
No idea what I’m doing really!
Just tried opening it in SODA PDF 5 and the same is true, The text goes off the side of the page and also the two columns overlap whilst the text still goes of the side of the page!
Now even more problems! Libre Office has updated and now it is showing in “Dark Mode”.
Black text on black background doesn’t help!
No idea how to correct it!
Managed to change to black on white!
Eventually resorted to the on line "print to PDF Custom pages, all seems “normal” - so far!
When you click on the text and see the font name in italics in the font name box, make a note of the font name. Check other text to find other fonts using a substitute font.
Close LibreOffice, download and install the missing fonts.
Open LibreOffice and the text should behave.
You can instead specify substitute fonts in the font replacement table in Tools - Options - LibreOffice - Fonts. Use the help button to find out how
Thanks EarnestAI for your help and patience!
I will remember this solution for future use of LibreOffice when creating PDF’s.
For this task, Chrome turned out to be the most expedient tool. 
Thanks again for your help.