If I failed to claim property tax in 2019 can I still get the tax break? I am not trying to make the claim on my 2020 taxes. Thank You

If you had enough itemized deductions to itemize for 2019 then you can amend your 2019 return to add the property tax you paid in 2019.    Did you enter other itemized deductions for 2019 last year----will adding the property tax get you to exceed your standard deduction?   

2019 Standard Deduction Amounts

Single $12,200   (+ $1650 65 or older)

Married Filing Separate  $12,200   (+ $1300 if 65 or older)

Married Filing Jointly $24,400   (+ $1300 for each spouse 65 or older)

Head of Household $18,350  (+ $1650 for 65 or older)

Look on line 9 of your 2019 Form 1040 to see your itemized/standard deduction amount

Take note that property taxes are a SCH A itemized deduction. If after adding the property taxes to your schedule A itemized deductions, if the total of all of your itemized deductions does not exceed your standard deduction, then it makes absolutely no difference to your tax liability. There would be no need to bother with it then.