Tmux

Resize pane

To resize a pane, you always use the default prefix ‘Ctrl + b’ followed by the colon (:) key. When you invoke these key combinations, it will prompt at the bottom of your screen. To resize the pane, you will need to use the prompt to resize the desired pane. For example, to resize a pane, you must type in the ‘resize-pane’ command followed by a hyphen (-) and either one of these options (D, U, R, L). These options are down, up, right, and left, respectively. Its work is to resize the pane in the direction provided.

 :resize-pane -D 10

С помощью мыши

This is one of the easiest alternatives to resize panes on Tmux. Using the mouse is much more convenient as it does not require any commands. This method is usually preferred since it provides more control over the pane size than the first method, which involves using the resize-pane command. Open the tmux.conf file and append the following line of code:

set -g mouse on

Once you are done, reload the tmux.conf file by executing the following line of code:

tmux source-file ~/.tmux.conf

Source:: https://www.fosslinux.com/80813/how-to-adjust-the-tmux-pane-size.htm