You can use your own icon (a PNG or JPEG image file) for your Extra on the cleaning booking form:
Overview Extras are additional items customers can select, that are outside the scope of the service you provide. For Extras to appear on your booking, you need to make sure your Extra is linked [...]
Overview You have the option of setting these items as “This Booking only” or “every booking” on a recurring booking: Extras Tip Price Adjustment This is useful when: the [...]
Go to Settings -> Extras Drag and drop an Extra to a new position in the list Your Extras will be displayed in your Booking Form identically to how they appear in this list.