As expected with any REST implementation, the Google Ads API does have Get methods for each resource, and is invoked as a standard HTTP GET using a resource name in its URL. The method returns the full resource with all of its fields populated.

For example, to get an individual campaign, send a standard HTTP GET using the campaign's resource name, and include the resource IDs for the customer ID and campaign ID:

GET /v6/customers/CUSTOMER_ID/campaigns/CAMPAIGN_ID HTTP/1.1
Authorization: Bearer ACCESS_TOKEN
developer-token: DEVELOPER_TOKEN

Because the Get method only returns a single object per response, and that object has all fields fully populated (as opposed to returning just the fields you're interested in), it is intended only for debugging and testing. For production code, always use the Search or SearchStream methods.