The standard deduction will be automatically recorded by TurboTax once any income is entered on the tax return. And the standard deduction amounts increased significantly for 2018, so even if you were entering itemized amounts, your return may not have switched to the standard deduction if the itemized amount total was still under the standard deduction amount.
To double check your return, take the steps below to preview your 1040 form before filing and see what amount is recorded on line 8 of the 1040 form.
https://ttlc.intuit.com/replies/3302322
Also, here is information on what the standard deduction amounts are for 2018:
https://ttlc.intuit.com/replies/4208574
