To install Laravel Horizon, you will be prompted to include the Laravel Horizon service on install. You simply just need to select it.

When you install Laravel Horizon, Spin will automatically choose to install Redis and set up a dedicated "Horizon" service for you. By default, the service runs the following command:
php artisan horizon
Once you run spin up in your local development environment, you can access the Laravel Horizon dashboard by visiting http://laravel.dev.test/horizon.
Migrating from Spin v2 to v3
Although Spin v3 doesn't ship with any breaking changes, there is a new structure for managing your configurations with Spin that you may want to upgrade to take advantage of.
Laravel Octane
Laravel Octane supercharges your application's performance by serving your Laravel application using high-powered application servers. With Spin Pro, Octane is powered by FrankenPHP, providing modern web features and exceptional performance.