Yes — plans are billed per Space, not per account. Each Space has its own plan and billing, so you only pay for what each Space needs.
On self-service plans (Starter, Growth, and Growth Plus), each account includes one Space. If your project requires multiple Spaces, this is available on Premium and Elite plans as specified in our Pricing Page. For details on how billing works across multiple Spaces, see: What if a customer has a project that requires 2 spaces? How does it get billed?