Scalable Way to Manage dynamic Email Templates in Laravel Notification Service

I'm working on a Laravel‐based centralized notification service that handles email and SMS for the whole system. Other microservices don’t need to know how it works just that they'll have a job with the same signature as ours then they just dispatch it with the right payload (recipient, template name, data, etc.) and we take care of the rest. What I’m wrestling with now is finding a simple, maintainable way to create and organize all the different email templates we’ll need one that won’t turn into a nightmare as we add more message types ... anyone ?