https://en.wikipedia.org/wiki/Economies_of_scale
The simple meaning of economies of scale is doing things more efficiently with increasing size.

https://en.wikipedia.org/wiki/Scalability
In an economic context, a scalable business model implies that a company can increase sales given increased resources.

https://minds.wisconsin.edu/handle/1793/9676
What is scalability?

https://corporatefinanceinstitute.com/resources/knowledge/strategy/scalability/

https://www.investopedia.com/terms/s/scalability.asp
Scalability is a characteristic of an organization, system, model, or function that describes its capability to cope and perform well under an increased or expanding workload or scope. A system that scales well will be able to maintain or even increase its level of performance or efficiency even as it is tested by larger and larger operational demands.