How can I increase the number of devices that you can include in a test run in DeviceFarm?

I found this on DeviceFarm documentation: https://docs.aws.amazon.com/devicefarm/latest/developerguide/limits.html

There is no limit to the number of devices that you can include in a test run. However, the maximum number of devices that Device Farm will test simultaneously during a test run is five. (This number can be increased upon request.)

How can I increase the number of devices? It doesn't specify where or how to request it...

I basically need this to run more test in parallel using the metered payment plan. Right now even if we have multiple tests making requests on the test project in device farm, only 5 tests are executed at a time, the remaining are pending.