Can there be a feature for clients to buy Features as addons themselves, instead of creating multiple tiered plans?

That way we can sell more flexible plans without trying to create the perfect plan for all of our clients. Also, the clients can buy addons later themselves, without have to talk to us and make custom changes in their plans if they want just one more certain feature, but it's part of bigger plan that they don't really need.

Let say a client just want to start with Funnel, Forms, Email Marketing and Chat widget. They can select these 4 features, and the price will adjust accordingly as we have set the prices for each feature ourselves.

Or we create one core offer with these 4 features.

Later on, the client wants Social Planner, Workflows and Community. They can see these features are possible but locked. And they can decide to unlock them one by one to add them to their plan and the monthly/yearly price is changed accordingly.

It's something like Whatsapp and Ad manager, but for features, and the price for them can prorate to the monthly/yearly cost.

Did I explain it well?

Or at least the ability to show all or some of the features in sidebar or tabs, but to be locked behind a paywall that sells the upgrade plan which include all.

The main idea is to make the software more automated and sell more features or plans by itself, rather than we as owners to have to build different plans for different types of needs. And to talk to every customer and manually upgrade their plans.

HubSpot is doing something similar with a paywall (see screenshots).

I want more flexibility in my Agency account.

Thank you!