xfce4-terminal doesn't read X resources, so that there is no unified way to make such configuration for all X clients which are xfce4-terminals (even remote ones.)
Start terminal maximized? has already been asked at reddit and answered; that's only a part of the complete correct answer:
Exec command in
There are two drawbacks with this answer:
/usr/share/applications/ is not the place for customizations; it would be overwritten by distro package upgrades.
It doesn't affect the launcher for the terminal, which in its turn uses
exo-open --launch TerminalEmulator. (This problem was pointed out in that thread at reddit.)
1. The place for customizations
Per the advice by killermoehre in https://mail.xfce.org/pipermail/xfce/2015-April/034375.html:
Never ever change files in
/usr (except for
/usr/local) directly. They will be overwritten on updates. If you want to make changes, copy them before into
~/.local/share/applications/ (create if necessary).
so, I've edited
/usr/share/applications/xfce4-terminal.desktop and saved it to
~/.local/share/applications/xfce4-terminal.desktop. The changed line looks like this:
2. Affecting the behavior of the launcher
By grepping through
~/.config after having configured a custom helper as the Terminal through the menu, I've found the other place that needs to be changed --
--maximize is present at two places):
X-XFCE-CommandsWithParameter=/usr/bin/xfce4-terminal --maximize -x "%s"
whereas I have the following