It’s not that you would *have* to use a third-party service such as S3 for remote assets — that is simply my preferred approach for assets in general.
If you are serving the assets as part of your Laravel application, they would be available through all of the domains your app serves by default. So your client (assuming the client is part of the Laravel app itself) could access the remote assets on the same domain as the client itself. Alternatively you could choose to access them off a single root domain if you prefer, you might just need to ensure that you don’t hit any issues with Content Security Policy headers that you may have in place for cross-domain requests for resources.
If I were you I’d simply give it a try in a development environment — it will become clear pretty quickly whether or not it will work for your use case.