tlmgr-paper
Manage paper size options of an TeX Live installation.
TLDR
Show the default paper size used by all TeX Live programs
$ tlmgr paper
Set the default paper size for all TeX Live programs to A4
$ sudo tlmgr paper [a4]
Show the default paper size used by a specific TeX Live program
$ tlmgr [pdftex] paper
Set the default paper size for a specific TeX Live program to A4
$ sudo tlmgr [pdftex] paper [a4]
List all available paper sizes for a specific TeX Live program
$ tlmgr [pdftex] paper --list
Dump the default paper size used by all TeX Live programs in JSON format
$ tlmgr paper --json
