I am answering my own post in case anyone else is searching for the same information.
I have recently purchased the HP smart tank 750. I can confirm that it can print folded booklets from the PC driver. When printing duplex or folded booklets the page margins stay the same at 3.3 mm all round.
The Android HP Smart App can print duplex but, I cannot find a way to print a folded booklet from there. So if anyone wishes to print a folded booklet they will need some kind of work around. Please can someone correct me if I am wrong. Hopefully, in the future HP will incorporate the ability to print a folded booklet in the Android app.
Adobe pdf reader and Microsoft Word on a PC are able to print folded booklets. So I suppose if you print from one of these applications to a pdf printer like "Microsoft print to pdf" then this will convert your document to a folded booklet layout. Then if you print this "folded booklet" file duplex from the Android HP smart app this should print the booklet.
On a PC its possible to enlarge the pages to 110% or whatever of the normal size in the folded booklet when printing. Open your pdf document then select the page enlargement (eg 110%) in the pdf reader with auto page centre. Then select booklet printing in your printer driver.
To enlarge pages when printing a booklet on the HP smart app you will need a two step process. On a PC open the pdf and select the page enlargement you require in the pdf reader. Then print this enlarged version to a pdf printer like "Microsoft print to pdf". Once you have the enlarged version of the pdf, then select the folded booklet option in the pdf reader and print again to a pdf printer like "Microsoft print to pdf". The result will be a pdf with enlarged pages and in a folded booklet layout. You should be able to print this as a folded booklet on the HP smart app using the duplex option.
I hope someone will find this information useful.
Kind regards
Chris
