<?php
declare(strict_types=1);
namespace Awesome\Requests;
use Illuminate\Foundation\Http\FormRequest;
class NewRequest extends FormRequest
{
    use DefaultMessages;  /** Add use trait */
    public function rules(): array
    {
        return [
            'name' => 'required|string|max:120',
            'start_date' => 'required|integer',
            'price' => 'nullable|numeric|min:0 ',
            'pay_link' => 'nullable|string|url|max:256',
            'video' => 'nullable|mimes:mp4,mov,avi',
            'confidentiality' => 'required|string|in:public,personal',
        ];
    }
}

<?php

var_export($newRequest->message());

[
  'name.required' => 'name is required',
  'name.string' => 'Value for name must be string',
  'name.max' => 'Maximal value for name is 120',
  'start_date.required' => 'start_date is required',
  'start_date.integer' => 'Value for start_date must be integer',
  'price.numeric' => 'Key price must be numeric',
  'price.min' => 'Minimal value for price is 0',
  'pay_link.string' => 'Value for pay_link must be string',
  'pay_link.url' => 'Key pay_link must be valid url',
  'pay_link.max' => 'Maximal value for pay_link is 256',
  'video.mimes' => 'Allowed formats for video: mp4, mov, avi',
  'confidentiality.required' => 'confidentiality is required',
  'confidentiality.string' => 'Value for confidentiality must be string',
  'confidentiality.in' => 'Allowed values for confidentiality: public, personal',
];

[
    'required',
    'integer',
    'numeric',
    'string',
    'url',
    'in',
    'min',
    'max',
    'mimes',
];

<?php
$this->addRuleNames(['test_rule']);
$this->addRulesToMessages(['test_rule' => 'test_message']);