You don't pay Turbotax. the balance due including any penalties are paid directly to the iRS.
if you do not have a current notice you can call the iRS or create an ID.me account to review your account transcript
https://sa.www4.irs.gov/secureaccess/ui/?TYPE=33554433&REALMOID=06-0006b18e-628e-1187-a229-7c2b0ad00...
there are various online tools to estimate your balance. if you underpay you get a bill from the IIRS for the balance or a refund check if you overpay
you have to option to submit payment online once ID.me account is created
https://www.irs.gov/payments
or mail payment to the location that depends on your state of residence
https://www.irs.gov/businesses/small-businesses-self-employed/where-to-send-your-individual-tax-acco...
if you filed late the penalty is 4.5% of balance due for each month late up to 5 months. you also owe a late payment penalty of .5%/month and a varying amount of interest.