Use Database Collation
--use-db-collation
By default, migration files are generated without collation setting.
This means php artisan migrate will create tables with the collation settings defined in the config/database.php file.
// config/database.php
return [
    'connections' => [
        'mysql' => [
            ...
            'charset' => 'utf8mb4',
            'collation' => 'utf8mb4_unicode_ci',
        ],
    ],
];
The --use-db-collation option will always generates migrations with the existing database collation settings.
Example
php artisan migrate:generate --use-db-collation
Will generate:
Schema::create('users', function (Blueprint $table) {
    $table->collation = 'utf8mb4_unicode_ci';
    $table->charset = 'utf8mb4';
    $table->bigIncrements('id');
    ...
});