I am trying to do something similar to this block of code - but with tax terms rather than custom fields in a post

its a bit beyond me

/**

• Add an auto-incrementing Project ID field to Design feedback posts */ function auto_assign_ids( $post_id, $post, $update ) {

  // Only assign ID to new design posts if ( $post->post_status == 'publish' && $post->post_type == 'designapprovalsystem' ) {

   // get the most recent Project post
   $project_args = array(
       'numberposts'       =>   2,
       'post_type'         =>   'designapprovalsystem',
       'orderby'           =>   'post_date',
       'order'             =>   'DESC'
   );
   $projects = get_posts( $project_args );
  
   // get the project_id of the prior post
   //get the custom field value of a post
   $last_id = get_post_meta( $projects[1]->ID, 'job_number', true );
  
   // increment
   $last_id++;
  
   // set the project_id of the current post
   update_post_meta( $post_id, 'job_number', $last_id );
  

  } } add_action( 'save_post', 'auto_assign_ids', 100, 3 );