How to find entities

is there a common way to find all entities for a given device? I am trying to work with a Roomba, and using the Allow to Clean only runs a very minimal cycle. I do not see any other functions to use, but have read where people are assigning cleaning cycles to specific areas, so there must be something available I am not seeing. thanks!

I don´t have any experience with Roomba. but one option for this is to go to Settings → Devices & Services → Devices tab and select the specific device.
This will open a new page showing all the available entities for the device, under headers like Controls, Sensors, Events, Configuration and/or Diagnostic.

Another option is to go to Settings → Devices & Services → Entities tab and filter the list for the specific device: Click on Filters, and select the device under Devices.

Is that what you are looking for?

Settings - Developer Tools - States is very useful also.