Hello,
App Engine does provide a local development environment that simulates a production environment. Kindly check the following documentation [1, 2] and switch on the link depending on the programming language that you are using.
I hope this helps.
Regards,
[1] https://cloud.google.com/appengine/docs/standard/python/tools/using-local-server
[2] https://cloud.google.com/datastore/docs/tools/datastore-emulator