Head to Page Settings > Privacy > and Toggle the Private option
Choose Google and copy the Authorized redirect URI
Open the Google Cloud Console
Assuming you already have a GCP project and Google Consent screen ready to roll then please do proceed with the steps below.
Step1 - APIs & Services > Credentials
Once logged into GCP, click on APIs and Services > Credentials and look for the + Create Credentials option
Step 2 - Choose OAuth client ID > Web Application > Use the Status Page Name
Step 3 - Choose Add URI and Paste this URI copied from your Sorry privacy settings.
Step 4 - Copy your new Client ID and Client Secret from Google and Paste these into your Sorry Privacy Settings
Final Step - Restrict the Sign-In to your domain and choose Save Changes.