First I make the .Xresources file into /home/tc directory with this configuration (it's an example of the wiki archlinux webpage shows):
URxvt.bufered: true
URxvt.background: black
URxvt.foreground: white
URxvt.cursorColor: green
URxvt.underLineColor: yellow
URxvt.font:xtf:Terminus:pixelsize=14:antialias=false
URxvt.boldfont:xtf:Terminus:bold: pixelsize=14:antialias=false
URxvt.perl-ext-common: default, tabbed
URxvt.title: Terminal rxvt
After i make .xinitrc into /home/tc directory too with:
xrdb -merge ~/.Xresource
I rebooted...
The result: no changes in rxvt terminal. It show the same screen with white background and black foreground color, the same font, etc. when I downloaded the xrvt.tcz extension. No one change.
By the way: When I downloaded the gnome-terminal.tcz can't be opened when i clicked on desktop icon. By the moment it don't worry me this.
Note: i'm using CorePlus v.11.0 with kernel tinycore-5.4.3 since Mars, 13 2020.