Can one modify the templates created by artisan migrate command?

Since Laravel 7 you can publish stubs using php artisan stub:publish.

The published stubs will be located within a stubs directory in the root of your application. Any changes you make to these stubs will be reflected when you generate their corresponding classes using Artisan make commands.

It's doable in a fairly logical way, at least in Laravel 5

Subclass MigrationCreator and override getStubPath(), just copying the function over from the original class (it will use your subclass's __DIR__)

<?php

namespace App\Database;

use Illuminate\Database\Migrations\MigrationCreator;

class AppMigrationCreator extends MigrationCreator
{
    public function getStubPath()
    {
        return __DIR__.'/stubs';
    }
}

Write a service provider to override migration.creator with your own subclass (it must be a deferred service provider, because you cannot override a deferred binding with an eager one):

<?php

namespace App\Database;

use Illuminate\Support\ServiceProvider;

class AppMigrationServiceProvider extends ServiceProvider
{
    protected $defer = true;

    public function register()
    {
        $this->app->singleton('migration.creator', function ($app) {
            return new AppMigrationCreator($app['files']);
        });
    }

    public function provides()
    {
        return ['migration.creator'];
    }
}

Add your service provider to config/app.php after the default ones.

Finally, copy vendor/laravel/framework/src/Illuminate/Database/Migrations/stubs alongside your MigrationCreator subclass (in this example it would become app/Database/stubs) and edit the templates to your needs.

Keep the DummyClass and DummyTable names, as they are replaced with str_replace() to create the actual migrations files.