The following script adds two empty lines before every new command line prompt using fish shell.
mkdir -p ~/.config/fish/functions echo 'function fish_prompt set_color $fish_color_cwd echo "" echo "" echo "" echo -n (prompt_pwd) set_color normal echo -n " > " end' > ~/.config/fish/functions/fish_prompt.fish
The following command adds the leading empty lines in bash:
echo "export PS1='\n\n$ '" >> ~/.bashrc