Yes, you can find this prior year tax liability for line 3 by getting a copy of your 2018 Form 760, and going to page 2, line 18.
To find 2018 returns in TurboTax: How do I access a prior year return?
2019 Virginia Form 760C Instructions Underpayment of Virginia Estimated Tax by Individuals, Estates and Trusts
2019 Virginia Form 760 Instructions Resident Individual Income Tax Booklet
@natyclementi
