Test-Laravel-Validation/app/Rules/Uppercase.php

<?php

namespace App\Rules;

use Closure;
use Illuminate\Contracts\Validation\ValidationRule;

class Uppercase implements ValidationRule
{
    /**
     * Run the validation rule.
     *
     * @param  \Closure(string): \Illuminate\Translation\PotentiallyTranslatedString  $fail
     */
    public function validate(string $attribute, mixed $value, Closure $fail): void
    {
        //
        if ((ucfirst($value)) !== $value)
        {
            $fail('The title does not start with an uppercased letter');
        }
    }
}