By default, inside vim the tab width is 8 spaces, we can reduce it using below steps.
Create a .vimrc file in ~(home dir) and add below content. Save it and now try.
filetype plugin indent on
" show existing tab with 4 spaces width
set tabstop=4
" when indenting with '>', use 4 spaces width
set shiftwidth=4
" On pressing tab, insert 4 spaces
set expandtab