I efiled my return after April 18th and did not choose to file an extension by mistake. The IRS has accepted the return and has provided me with expected refund date?

What is your question?

The IRS accepts and processes tax returns that are filed late, and you can still get a refund even though you filed late. If you are getting a refund there is no penalty for filing late.

The "expected refund date" comes from TurboTax, not from the IRS, and it is essentially meaningless. TurboTax just gives you a date that is 21 days after you file. It's not based on specific information about your tax return, and it doesn't mean that you will get your refund by that date.