If you read the File Geodatabase using a FeatureReader, you'll have the option of either reading the data, the schema, or both, see here under the heading "Schema/Data Features":

https://docs.safe.com/fme/html/FME_Desktop_Documentation/FME_Transformers/Transformers/featurereader.htm

@pbonagiri​ If you use the most recent version of FME 2022 then the domains will also be include in the schema list attributes created by the <schema> port that @david_r​ mentions above.

If you want the detailed schema then you can use the approach suggested here using an Esri XML Workspace document. At the very bottom is a link to an answer by @ebygomm​ with the arcpy you can use in PythonCaller to export the XML Workspace Document.