/etc/texmf/dvips/config.landscapeplus is in texpower 0.2-7.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 | @ a4l 297mm 210mm
@+ %%PaperSize: a4l
@+ ! %%DocumentPaperSizes: a4l
@+ %%BeginPaperSize: a4l
@+ <</PageSize [842 595]>>setpagedevice
@+ %%EndPaperSize
@ letterl 11in 8.5in
@+ %%PaperSize: letterl
@+ ! %%DocumentPaperSizes: letterl
@+ %%BeginPaperSize: letterl
@+ <</PageSize [792 612]>>setpagedevice
@+ %%EndPaperSize
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