Please help to create a custom link field of the story summary should be in the task creation screen.
Example: Below screenshot story created in detail and the summary name is Story test 2. This has to be auto-populated on the task creation page by adding a custom field.
Screenshot of Task creation screen
If I understand you correctly, you want to populate a field on the create screen based on the value of another field during the create process. Correct? If so, that cannot be done right now with Jira Cloud. You would need something like ScriptRunner Behaviours, but I am not sure that it could do that, and it's still in Beta.