At the time of this writing, there is no geoprocessing tool to identify the feature classes and tables that reference a given domain, but there are Python functions that can list the properties of these structures in a geodatabase. Among the properties are the referenced domains.
Copy the link address of the sample script and file geodatabase provided below and open it in a browser to download the .zip file.
The script demonstrates how Python functions might be used to list the domains and other properties of feature classes and tables. Domains can be associated with fields in a feature class or table; they can additionally be set for fields categorized by a subtype.
When the script is run from the toolbox, the geodatabase is specified as an input parameter to the tool. The output is displayed in the execution status window > Details section.