How to get number and put header on laravel-excel export

Its been more than 2 years to the question but i will still answer it as it may be helpful. I have just added 1 title row but one can add any amount of rows needed. I have attached a screenshot below as how the export looks like.

<?php

namespace App\Exports;

use App\Models\Member;
use Illuminate\Support\Collection;
use Maatwebsite\Excel\Concerns\FromCollection;
use Maatwebsite\Excel\Concerns\WithCustomStartCell;
use Maatwebsite\Excel\Concerns\ShouldAutoSize;
use Maatwebsite\Excel\Concerns\WithHeadings;
use Maatwebsite\Excel\Concerns\WithStyles;
use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
use Maatwebsite\Excel\Concerns\WithMapping;
use Maatwebsite\Excel\Concerns\WithEvents;
use Maatwebsite\Excel\Events\AfterSheet;

class MembersExport implements WithEvents, WithMapping, FromCollection, WithCustomStartCell, ShouldAutoSize, WithHeadings, WithStyles {
    protected $index = 0;

    public function registerEvents(): array {

        return [
            AfterSheet::class => function(AfterSheet $event) {
                $sheet = $event->sheet;

                $sheet->mergeCells('B2:H2');
                $sheet->setCellValue('B2', "Members list.");

                $styleArray = [
                    'font' => [
                        'size' => '20px',
                        'bold' => true,
                    ],
                    'alignment' => [
                        'horizontal' => \PhpOffice\PhpSpreadsheet\Style\Alignment::HORIZONTAL_CENTER,
                    ],
                ];

                $cellRange = 'B2:H2';
                $event->sheet->getDelegate()->getStyle($cellRange)->applyFromArray($styleArray);
            },
        ];
    }

    public function startCell(): string {
        return 'B3';
    }

    /**
     * @return Collection
     */
    public function collection(): Collection {
        return Member::query()->select(['first_name', 'middle_name', 'last_name', 'gender', 'address', 'mobile'])->get();
    }

    public function prepareRows($rows): Collection
    {
        $rows = collect($rows);
        return $rows->transform(function ($member) {
            $member->gender = $member->gender == 'M' ? 'Male' : 'Female';
            return $member;
        });
    }

    public function map($row): array
    {
//        $fields = [
//            ++$this->index,
//            $row->first_name,
//            $row->middle_name,
//            $row->last_name,
//            $row->gender,
//            $row->address,
//            $row->mobile,
//        ];
//        return $fields;

        return array_merge(['srno' => ++$this->index], $row->toArray());
    }

    public function headings(): array {
        return [
            'Sr No',
            'First Name',
            'Middle Name',
            'Last Name',
            'Gender',
            'Address',
            'Contact',
        ];
    }

    public function styles(Worksheet $sheet) {
        $styleArray = [
            'font' => [
                'bold' => true,
            ],
            'borders' => [
                'outline' => [
                    'borderStyle' => \PhpOffice\PhpSpreadsheet\Style\Border::BORDER_THIN,
                ],
            ],
            'fill' => [
                'fillType' => \PhpOffice\PhpSpreadsheet\Style\Fill::FILL_SOLID,
                'color' => ['rgb' => 'b6c2d4']
            ],
        ];
        $sheet->getStyle('B3:H3')->applyFromArray($styleArray);
        $sheet->getStyle('B')->getAlignment()->setHorizontal('center');
        $sheet->getStyle('H')->getAlignment()->setHorizontal('left');
    }
}

protected $index = 0;

public function map($row): array
{
     $fields = [
         ++$this->index,
         Date::dateTimeToExcel($row->date),
         $row->title,
         $row->link,
         $row->file,
         $row->description,
     ];
     return $fields;
}

We can utilize the map function to create numbering in Excel exports by adding an additional variable to hold the numbers.

protected $index = 0;

public function map($employee): array
{
    return [
        ++$this->index,
        $employee->client->name,
        $employee->account->name,
        Carbon::parse($employee->created_at)->format('m/d/Y H:i'),
    ];
}

public function headings(): array
{
    return [
        'NO',
        'UNIT',
        'NAME',
        'DATE',
    ];
}