users table
SNO user_name   manager
1    vani        Ramya
2    ramya       geetha
3    priya       ramya
4    mani        ramya
5    latha       vani
6.   hema        Anitha

project table
project_id    name   customer_code  owner
1              x      C1             ramya
2              xx     c2             vani
3              x1     c2             priya
4              x2     c3             geetha
5              x3     c4             mani
6              x4     c5             latha

$users = DB::table('users as a')
->select('a.user_name')
->leftJoin('users as b', 'a.manager', '=', 'b.user_name')
->where('a.user_name','Ramya')
->orwhere('a.manager','Ramya')
->orwhere('b.manager','Ramya')
->get();