There is no such thing as "microservices", it's just services, otherwise known as a service-oriented architecture (SOA). A service is a logical grouping of functionality as it makes sense in your business domain. A small service for a large company can be bigger than the entire product of a startup; there is no standard unit of measure.

Computers also don't care how code is deployed and different services can be bounded by classes, or namespaces, or assemblies, or packages, or processes, or completely separate APIs reached over the internet on the other side of the planet.

Microservices can perhaps be defined as more of a deployment model but even then it's 99% about the team and organization structure. As companies get larger, there is a trend towards smaller teams in charge of separate functionalities that create, deploy, and operate their own service. This can be effective in managing complexity and creating efficiency, although definitely not absolutely necessary.

All that being said, outside of the major software companies, I have seen exactly 0 uses of microservices where the benefits were worth the effort, if any benefits even appeared at all.