diff --git a/packages/analytics/__tests__/analytics.test.ts b/packages/analytics/__tests__/analytics.test.ts
index 35e66f8a7f..0120ca00ee 100644
--- a/packages/analytics/__tests__/analytics.test.ts
+++ b/packages/analytics/__tests__/analytics.test.ts
@@ -4,6 +4,7 @@ import {
   firebase,
   getAnalytics,
   initializeAnalytics,
+  getGoogleAnalyticsClientId,
   logEvent,
   setAnalyticsCollectionEnabled,
   setSessionTimeoutDuration,
@@ -711,6 +712,10 @@ describe('Analytics', function () {
       expect(initializeAnalytics).toBeDefined();
     });
 
+    it('`getGoogleAnalyticsClientId` function is properly exposed to end user', function () {
+      expect(getGoogleAnalyticsClientId).toBeDefined();
+    });
+
     it('`logEvent` function is properly exposed to end user', function () {
       expect(logEvent).toBeDefined();
     });
diff --git a/packages/analytics/lib/modular/index.d.ts b/packages/analytics/lib/modular/index.d.ts
index 5cc60dc669..83a66da8fb 100644
--- a/packages/analytics/lib/modular/index.d.ts
+++ b/packages/analytics/lib/modular/index.d.ts
@@ -23,6 +23,14 @@ export declare function initializeAnalytics(
   options?: FirebaseAnalyticsTypes.AnalyticsSettings,
 ): Analytics;
 
+/**
+ * Retrieves a unique Google Analytics identifier for the web client.
+ *
+ * @param analyticsInstance - Instance of analytics (web - only)
+ *
+ */
+export declare function getGoogleAnalyticsClientId(analyticsInstance: Analytics): Promise<string>;
+
 /**
  * Log a custom event with optional params. Note that there are various limits that applied
  * to event parameters (total parameter count, etc), but analytics applies the limits during
@@ -605,10 +613,14 @@ export function getAppInstanceId(analytics: Analytics): Promise<string | null>;
  * Gives a user a unique identification.
  *
  * @param analytics Analytics instance.
- * @param id Set to null to remove a previously assigned ID from analytics
- * events
+ * @param id Set to null to remove a previously assigned ID from analytics events
+ * @param options Additional options that can be passed to Analytics method calls such as logEvent, etc.
  */
-export function setUserId(analytics: Analytics, id: string | null): Promise<void>;
+export function setUserId(
+  analytics: Analytics,
+  id: string | null,
+  options?: AnalyticsCallOptions,
+): Promise<void>;
 
 /**
  * Sets a key/value pair of data on the current user. Each Firebase project can have up to 25 uniquely named (case-sensitive) user properties.
diff --git a/packages/analytics/lib/modular/index.js b/packages/analytics/lib/modular/index.js
index dd05ed9e4b..0a2e26aa00 100644
--- a/packages/analytics/lib/modular/index.js
+++ b/packages/analytics/lib/modular/index.js
@@ -64,6 +64,16 @@ export function initializeAnalytics(app, options) {
   return getApp(app.name).analytics();
 }
 
+/**
+ * Retrieves a unique Google Analytics identifier for the web client.
+ *
+ * @param {FirebaseAnalytics} analytics - Instance of analytics (web - only)
+ * @returns {string}
+ */
+export function getGoogleAnalyticsClientId(analytics) {
+  throw new Error('getGoogleAnalyticsClientId is web-only and not yet supported.');
+  return analytics;
+}
 /**
  * Log a custom event with optional params.
  * @param {FirebaseAnalytics} analytics - Analytics instance.