Update a list item in sharepoint online using FLOW

I would like to update a sharepoint list item using ms flow but need to use the “Send an HTTP request to sharpoint” option the update list action will not work due to some complex options in the form.

Does any one have an example of this procedure, searching online shows procedures for updating a list name but I wish to update a list item field with a new value

Example would incluse

Method (i guess this will be POST) Uri /_api/lists/getByTitle(‘Test Request List)/ID variable Headers ? Body ?