Power and Energy Manager is an app offering the creation of several different kinds of tools or automations related to power and energy, including:
From the sidebar of your hub, navigate to Automations and select Add Automation or Add Built-In Automation:

Choose Power and Energy Manager from the list of built-in automation apps.
(If already installed, simply navigate to Automations, then expand the list to view existing child apps if needed. To create a new child app — any of the types mentioned above — open the parent app and select the desired type.)