FormTemplate

// Create a FieldElement
const fieldElement = new FieldElement({
  fieldName: "inspector",
  label: "Inspector name"
});

// Create a TextElement
const textElement = new TextElement({
  textFormat: "markdown",
  text: "**This text is bold.**"
});

// Create the group element and pass in the field and text elements
const groupElement = new GroupElement({
  label: "This is a group",
  elements: [fieldElement, textElement]
});

// Create the Form template and pass in elements
const formTemplate = new FormTemplate({
  title: "Inspector report",
  description: "Enter all relevant information below",
  elements: [groupElement] // Add all elements to the template
});

// Add a new feature form with grouped fields
const form = new FeatureForm({
  container: "form",
  groupDisplay: "sequential", // only display one group at a time
  formTemplate: formTemplate // set it to template created above
});

// Add a formtemplate to a feature layer
const featureLayer = new FeatureLayer({
 url: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/ServiceRequest/FeatureServer/0",
 outFields: ["*"],
 formTemplate: formTemplate
});
map.add(featureLayer);

// Add a formtemplate to a subtype sublayer
const sublayer = new SubtypeSublayer({
  layer: featureLayer,
  subtype: "1",
  formTemplate: formTemplate
});

// Add a formtemplate to the Editor's layerInfos
const editor = new Editor({
  view: view,
  layerInfos: [
  {
    layer: featureLayer,
    formTemplate: formTemplate
  }]
});