How to add Title to Excel Sheet using Maatwebsites

I am trying to export my report to excel in Laravel-5.8 project using Maatwebsites:

In Laravel-5.8, I am trying to export to Excel using Maatwebsite:

<?php

namespace App\Exports;

use App\User;
use Carbon\Carbon;
use Maatwebsite\Excel\Concerns\FromCollection;
use Maatwebsite\Excel\Concerns\Exportable;
use Maatwebsite\Excel\Concerns\FromQuery;
use Maatwebsite\Excel\Concerns\WithHeadings;
use Maatwebsite\Excel\Concerns\ShouldAutoSize;
use Maatwebsite\Excel\Concerns\WithEvents;
use Maatwebsite\Excel\Events\BeforeExport;
use Maatwebsite\Excel\Events\BeforeWriting;
use Maatwebsite\Excel\Events\BeforeSheet;
use Maatwebsite\Excel\Events\AfterSheet;

use Maatwebsite\Excel\Concerns\FromView;
use PhpOffice\PhpSpreadsheet\Shared\Date;
use PhpOffice\PhpSpreadsheet\Style\NumberFormat;
use Maatwebsite\Excel\Concerns\WithColumnFormatting;
use Maatwebsite\Excel\Concerns\WithMapping;
use \Maatwebsite\Excel\Sheet;
use Maatwebsite\Excel\Concerns\RegistersEventListeners;
use Illuminate\Support\Facades\DB;

use Auth;


class EmployeesGoalPublishedExport implements FromCollection, ShouldAutoSize, WithHeadings
{


    private $headings = [
        'Staff ID', 
        'Name',
        'Gender',
        'Official Email',
        'Department',
        'HOD',
        'HRBP',
        'Line Manager',
        'Goal Status'
    ];




    public function collection()
    {
        $userCompany = Auth::user()->company_id;
        $userEmployee = Auth::user()->employee_id;
        $userId = Auth::user()->id;
        $employeecode = Auth::user()->employee_code;

        $identities = DB::table('appraisal_identity')->select('id')->where('company_id', $userCompany)->where('is_current', 1)->pluck('id');
        $publishedgoals = AppraisalGoal::select('employee_code')->where('is_published', 1)->where('appraisal_identity_id', $identities)->where('company_id', $userCompany)->groupBy('employee_code')->get();  


        $published_goals = DB::table('hr_employees AS e')
                    ->join('hr_employees AS em','em.employee_code','=','e.line_manager_id')
                    ->join('hr_departments AS d','e.department_id','=','d.id')
                    ->join('hr_employees AS eh','eh.employee_code','=','d.dept_head')
                    ->join('hr_employees AS eb','eb.employee_code','=','d.hr_business_partner_id')
                    ->join('appraisal_goals AS ag','ag.company_id','=','e.company_id')
                     ->select(
                        'e.employee_code as staff_id',
                        DB::raw('CONCAT(e.first_name, " ", e.last_name) AS full_name'),
                        DB::raw('IF(e.gender_code = 0, "Female", "Male") AS gender'),      
                        'e.email as official_email',
                        'd.dept_name',

                        DB::raw('CONCAT(eh.first_name, " ", eh.last_name) AS hod_name'),
                        DB::raw('CONCAT(eb.first_name, " ", eb.last_name) AS hrbp_name'),
                        DB::raw('CONCAT(em.first_name, " ", em.last_name) AS line_manager'),
                        DB::raw('(CASE WHEN ag.is_approved = 3 THEN "Approved" WHEN ag.is_approved = 2 THEN "Not Approved" WHEN ag.is_approved = 1 THEN "Awaiting Approval" ELSE "Draft" END) AS goal_status')
                 )
                    ->whereIn('e.employee_code', $publishedgoals)
                    ->where('e.company_id', $userCompany)
                    ->where('e.hr_status', 0) 
                ->distinct()
                ->get();

            $published_goals = $published_goals->unique('staff_id');
            $published_goals = array_slice($published_goals->values()->all(), 0, 5, true);          

                 return $published_goals;
    } 

    public function headings() : array
    {

                        return $this->headings;	//english
    }    

    public function registerEvents(): array
    {
        return [
            AfterSheet::class    => function(AfterSheet $event) {
                $cellRange = 'A1:I1'; // All headers
                $event->sheet->getDelegate()->getStyle($cellRange)->getFont()->setSize(14);
            },

        ];
    }     
}

How to I add General Title on the sheet on top of the headings, and also center the Title.

How do I make the headings and the Title bold.

Thanks