The topic of generating large test datasets has come up many times before. If you search this forum on the topic, you’ll find this thread.
Essentially, you’ll need to generate a large dummy dataset yourself as a CSV file and then import it, or parse the CSV via your own code and push it it in via the REST API.
The scope of the dataset and all the extra features of Jira that should be created and to what extent are described in the Testing your app on a large DC page. It’s a big requirement set, so utilize the REST API for mass creating things like all the Users, Screen schemes, Issue Types, Components etc rather than doing it manually.