Page layout for 'new' printer

[drobble]

Hello,
I’m using for quite a while Libreoffice with a HP MFPM1536 to print Index cards (6" x 4") using the page layout "Japanese Postcard (100mm x 148mm) which is attached to this printer.
I now added a Lexmark E260 to the system but noticed that for this printer there is no page size of 100mm x 148mm as for the HP printer.
I’m assuming the available page layouts are determined by the driver installed on the system.
But perhaps I am wrong and I could define the new page size for the E260 in Libreoffice.
Perhaps someone can shed some light on how I could fix the problem,
setup in Libreoffice or a different printer driver or something totally different?
Please assume I want to use this “6x4” format and no other gimmicks or workarounds
Any ideas?
Any constructive help is much appreciated.

PS I’m using LO v24.2.5.2 on Linux

[drobble]

PS: the problem is NOT to define a page style in this format, the problem is to bring the printer to the point were it’s printing the full contents of the document in the proper format.
Thx

[EarnestAl]

According to Lexmark E260 printer manual, the smallest size supported is A6 (105 x 148) but with the proviso A6 is supported only for grain long papers, whatever that means

[drobble]

That’s a bummer.
However, I figured out a way to use the A6 format to print my index cards (They are very similar in size).
Thanks