Automations created in Hue Essentials can be started from a widget on your phone.
First you need to create an automation with an External event and save it. Configure the conditions and actions however you want. See for more information: Automation that can be triggered externally
Now create a widget.
Android
The 1x1 action widget can start an automation. See for more information: How can I add widgets to my Home screen?
iOS & iPadOS
On Apple devices you can use a Siri Shortcuts widget to start an automation. See for more information: How do I use Siri Shortcuts?