add_filter('op_get_login_cashdrawer_data',function($session_response_data){
    $buttons = array();
    $buttons[] = 'cart-note';
    $buttons[] = 'shipping';
    $buttons[] = 'pickup';
    $buttons[] = 'cart-discount';
    $buttons[] = 'custom-item';
    $buttons[] = 'custom-tax';
    $buttons[] = 'seller';
    $buttons[] = 'coupon';
    $buttons[] = 'fee'; 
    $session_response_data['setting']['pos_cart_buttons'] = $buttons;
    return $session_response_data;  
},11,1);

Auto 3 first button display , other inside the more icon.