"Open Core", where the core product is open source and you provide closed source extensions, generally high-value integrations and enteprise-y features like SSO, active directory support, etc.
"Paid Services" where you have offerings on top of the open product. You might offer trainings, consultations, support contracts, custom development work (e.g. aforementioned high-value integrations). Also very common is to offer a fully-managed SaaS experience, but I wouldn't expect that to be your key to success; many open-core businesses fail expecting that full hosting to be more attractive than it is.
It's becoming more popular to offer "on-prem"/"self-hosted" support. Cloud costs are going to get cut after 3rd party products among your customers, so getting your product counted in column B gives you a little edge. Even if they need to cut their support contract down they're still using your product and are more likely to come back when the storm is over.