Selenium Grid: Do Features always run in parallel and Scenarios always run in series? Is this customizable?

Does Selenium Grid always run Features in parallel and always run Scenarios in series? Can you specify that certain features run in series or that certain scenarios run in parallel? I am just interested in understanding the flexibility and the rules/constraints.

Tried finding this information online. Selenium Grid can be customized, but not sure about customization that tells the grid what should run in parallel and what should run in series (some thing have to run in series if there is a dependency between tests ... ideally, there would be no dependencies between tests).

Some info found online:

Selenium Grid allows a lot of flexibility with by using a json configuration file: Creating a JSON configuration file

In addition to the json configuration file, you can do additional customization using custom servlets: Custom Servlets

However, couldn't find any information about how Selenium-Grid knows what parts of the test (features/scenarios/steps) need to be run in parallel.

If you want different series of testing scenarios, you can create test suites with testng or junit, that will guarranty the specific orders for some scenarios.

The intent of selenium-grid is to run tests in parallel in nodes, but if you do not want to run in parallel, I think that the approach is use just one node