diff --git a/wp-includes/block-supports/typography.php b/wp-includes/block-supports/typography.php
index 34345ca4ec..b31464c12d 100644
--- a/wp-includes/block-supports/typography.php
+++ b/wp-includes/block-supports/typography.php
@@ -471,6 +471,7 @@ function wp_get_computed_fluid_typography_value( $args = array() ) {
  * @since 6.1.1 Adjusted rules for min and max font sizes.
  * @since 6.2.0 Added 'settings.typography.fluid.minFontSize' support.
  * @since 6.3.0 Using layout.wideSize as max viewport width, and logarithmic scale factor to calculate minimum font scale.
+ * @since 6.4.0 Added configurable min and max viewport width values to the typography.fluid theme.json schema.
  *
  * @param array $preset                     {
  *     Required. fontSizes preset value as seen in theme.json.
@@ -517,14 +518,21 @@ function wp_get_typography_font_size_value( $preset, $should_use_fluid_typograph
 		: array();
 
 	// Defaults.
-	$default_maximum_viewport_width       = isset( $layout_settings['wideSize'] ) && ! empty( wp_get_typography_value_and_unit( $layout_settings['wideSize'] ) ) ? $layout_settings['wideSize'] : '1600px';
+	$default_maximum_viewport_width       = '1600px';
 	$default_minimum_viewport_width       = '320px';
 	$default_minimum_font_size_factor_max = 0.75;
 	$default_minimum_font_size_factor_min = 0.25;
 	$default_scale_factor                 = 1;
-	$has_min_font_size                    = isset( $fluid_settings['minFontSize'] ) &&
-		! empty( wp_get_typography_value_and_unit( $fluid_settings['minFontSize'] ) );
-	$default_minimum_font_size_limit      = $has_min_font_size ? $fluid_settings['minFontSize'] : '14px';
+	$default_minimum_font_size_limit      = '14px';
+
+	// Defaults overrides.
+	$minimum_viewport_width = isset( $fluid_settings['minViewportWidth'] ) ? $fluid_settings['minViewportWidth'] : $default_minimum_viewport_width;
+	$maximum_viewport_width = isset( $layout_settings['wideSize'] ) && ! empty( wp_get_typography_value_and_unit( $layout_settings['wideSize'] ) ) ? $layout_settings['wideSize'] : $default_maximum_viewport_width;
+	if ( isset( $fluid_settings['maxViewportWidth'] ) ) {
+		$maximum_viewport_width = $fluid_settings['maxViewportWidth'];
+	}
+	$has_min_font_size       = isset( $fluid_settings['minFontSize'] ) && ! empty( wp_get_typography_value_and_unit( $fluid_settings['minFontSize'] ) );
+	$minimum_font_size_limit = $has_min_font_size ? $fluid_settings['minFontSize'] : $default_minimum_font_size_limit;
 
 	// Font sizes.
 	$fluid_font_size_settings = isset( $preset['fluid'] ) ? $preset['fluid'] : null;
@@ -551,7 +559,7 @@ function wp_get_typography_font_size_value( $preset, $should_use_fluid_typograph
 	 * in order to perform comparative checks.
 	 */
 	$minimum_font_size_limit = wp_get_typography_value_and_unit(
-		$default_minimum_font_size_limit,
+		$minimum_font_size_limit,
 		array(
 			'coerce_to' => $preferred_size['unit'],
 		)
@@ -600,8 +608,8 @@ function wp_get_typography_font_size_value( $preset, $should_use_fluid_typograph
 
 	$fluid_font_size_value = wp_get_computed_fluid_typography_value(
 		array(
-			'minimum_viewport_width' => $default_minimum_viewport_width,
-			'maximum_viewport_width' => $default_maximum_viewport_width,
+			'minimum_viewport_width' => $minimum_viewport_width,
+			'maximum_viewport_width' => $maximum_viewport_width,
 			'minimum_font_size'      => $minimum_font_size_raw,
 			'maximum_font_size'      => $maximum_font_size_raw,
 			'scale_factor'           => $default_scale_factor,
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 56ef5085ed..3e8a5a1287 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.4-alpha-56534';
+$wp_version = '6.4-alpha-56535';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.