While using Termux when we have to use keys like control alt or up or down arrow we use Touch keyboard which comes in by default with termux app.
To access extra keys while using termux, Many people advice to download Hackers Keyboard from Play Store, but It take your data and space and some how, hard to use it because have small buttons.
If you want to use extra keys in termux you can use some commands provided by the official termux website but creating a properties file with the code provided by the termux is a little bit work.
How to Enable Basic and Arrow Keys in Termux:
mkdir $HOME/.termux/ ;echo "extra-keys = [['ESC','/','-','HOME','UP','END'],['TAB','CTRL','ALT','LEFT','DOWN','RIGHT']]" >> $HOME/.termux/termux.properties && termux-reload-settings && sleep 1 && logout
How to Enable Function Keys in Termux:
mkdir $HOME/.termux/ ;echo "extra-keys = [['F1','F2','F3','F4','F5','F6','F12'],['ESC','TAB','CTRL','ALT','-','DOWN','UP']]" >> $HOME/.termux/termux.properties && termux-reload-settings && sleep 1 && logout
You can change the F1 with F7 or any function key in the command to enable that key in termux.
How to Enable All Keys in Termux:
mkdir $HOME/.termux/ ;echo "extra-keys = [['F1','F2','F3','F4','F5','F6','F7'],['ESC','/','-','HOME','UP','END','PGUP'],['TAB','CTRL','ALT','LEFT','DOWN','RIGHT','PGDN']]" >> $HOME/.termux/termux.properties && termux-reload-settings && sleep 1 && logout
This is how you can enable all keys in termux. This is a simple step just copy and paste the above command.