Index: src/wp-includes/class-wp-theme-json-resolver.php
===================================================================
--- src/wp-includes/class-wp-theme-json-resolver.php	(revision 55985)
+++ src/wp-includes/class-wp-theme-json-resolver.php	(working copy)
@@ -314,6 +314,11 @@
 
 			// Classic themes without a theme.json don't support global duotone.
 			$theme_support_data['settings']['color']['defaultDuotone'] = false;
+
+			// Allow themes to enable link colors via theme_support.
+			if ( current_theme_supports( 'link-color' ) ) {
+				$theme_support_data['settings']['color']['link'] = true;
+			}
 		}
 		$with_theme_supports = new WP_Theme_JSON( $theme_support_data );
 		$with_theme_supports->merge( static::$theme );