If you use the vim above v8.2, you can check with :help tmux-integration.
If you experience issues when running Vim inside tmux, here are a few hints.You can comment-out parts if something doesn't work (it may depend on theterminal that tmux is running in):
if !has('gui_running') && &term =~ '^\%(screen\|tmux\)'" Better mouse support, see :help 'ttymouse' set ttymouse=sgr" Enable true colors, see :help xterm-true-color let &termguicolors = v:true let &t_8f = "\<Esc>[38;2;%lu;%lu;%lum" let &t_8b = "\<Esc>[48;2;%lu;%lu;%lum"" Enable bracketed paste mode, see :help xterm-bracketed-paste let &t_BE = "\<Esc>[?2004h" let &t_BD = "\<Esc>[?2004l" let &t_PS = "\<Esc>[200~" let &t_PE = "\<Esc>[201~"" Enable focus event tracking, see :help xterm-focus-event let &t_fe = "\<Esc>[?1004h" let &t_fd = "\<Esc>[?1004l"" Enable modified arrow keys, see :help xterm-modifier-keys execute "silent! set <xUp>=\<Esc>[@;*A" execute "silent! set <xDown>=\<Esc>[@;*B" execute "silent! set <xRight>=\<Esc>[@;*C" execute "silent! set <xLeft>=\<Esc>[@;*D"endif