The Title field is a configurable text field for your page titles. This field is a specific configuration of a Rich Text (aka Structured Text) field that limits the styling options.
The Title field is capable of outputting the content directly into HTML, which makes it different from the Key Text field which only outputs a single string.
Assign the Title field a Field name, API ID, and Field placeholder text that will display in the entry editor.
Next you can toggle on & off the heading options that will be available for the Title field. These include headers 1 through 6.
The following defines a single heading (a page title, for example):
"single": "heading1, heading2, heading3",
"label": "Page Title",
"placeholder": "Enter page title...",
"type": (string, required) "StructuredText"
"config": (object, optional) Options listed below
"placeholder": (string) Sets a user-friendly placeholder into the field
"label": (string) Sets the label that shows up for the field in the entry editor
"single": (string) Coma-separated heading options.
"useAsTitle": (boolean) If set to true, will use this field for the document name on the document listing page