diff -u b/core/modules/datetime/config/schema/datetime.schema.yml b/core/modules/datetime/config/schema/datetime.schema.yml
--- b/core/modules/datetime/config/schema/datetime.schema.yml
+++ b/core/modules/datetime/config/schema/datetime.schema.yml
@@ -116,14 +116,26 @@
 field.formatter.settings.daterange_default:
   type: field.formatter.settings.datetime_default
   label: 'Date range default display format settings'
+  mapping:
+    separator:
+      type: string
+      label: 'Separator'
 
 field.formatter.settings.daterange_plain:
   type: field.formatter.settings.datetime_plain
   label: 'Date range plain display format settings'
+  mapping:
+    separator:
+      type: string
+      label: 'Separator'
 
 field.formatter.settings.daterange_custom:
   type: field.formatter.settings.datetime_custom
   label: 'Date range custom display format settings'
+  mapping:
+    separator:
+      type: string
+      label: 'Separator'
 
 field.widget.settings.daterange_datelist:
   type: mapping
diff -u b/core/modules/datetime/src/Plugin/Field/FieldFormatter/DateRangeCustomFormatter.php b/core/modules/datetime/src/Plugin/Field/FieldFormatter/DateRangeCustomFormatter.php
--- b/core/modules/datetime/src/Plugin/Field/FieldFormatter/DateRangeCustomFormatter.php
+++ b/core/modules/datetime/src/Plugin/Field/FieldFormatter/DateRangeCustomFormatter.php
@@ -27,7 +27,6 @@
    */
   public static function defaultSettings() {
     return [
-      'date_format' => DATETIME_DATETIME_STORAGE_FORMAT,
       'separator' => '-',
     ] + parent::defaultSettings();
   }
diff -u b/core/modules/datetime/src/Plugin/Field/FieldFormatter/DateRangeDefaultFormatter.php b/core/modules/datetime/src/Plugin/Field/FieldFormatter/DateRangeDefaultFormatter.php
--- b/core/modules/datetime/src/Plugin/Field/FieldFormatter/DateRangeDefaultFormatter.php
+++ b/core/modules/datetime/src/Plugin/Field/FieldFormatter/DateRangeDefaultFormatter.php
@@ -28,7 +28,6 @@
    */
   public static function defaultSettings() {
     return [
-      'format_type' => 'medium',
       'separator' => '-',
     ] + parent::defaultSettings();
   }