I have this .vimrc config file

$ cat ~/.vimrc
call plug#begin('~/.vim/plugged')
  Plug 'alvan/vim-closetag'

  " below only work with vim9
  Plug 'yegappan/lspl
call plug#end()
$

This .vimrc is used by users with vim8 others with vim9.

How could I execute the line

Plug 'yegappan/lspl

only in case the vim which loads it is vim9 ?