Deductions only reduce your income so you get taxed on a lower amount. It's not a 1:1 savings on the tax. You only save the amount of your tax bracket. Like if you are in the 25% tax rate a $100 deduction only reduces the tax by $25.
And also all your deductions have to be more than the Standard Deduction to be used. So then only the amount that puts you over the Standard Deduction makes a difference.
For 2020 the standard deduction amounts are:
Single 12,400 + 1,650 for 65 and over or blind (14,050)
HOH 18,650 + 1,650 for 65 and over or blind
Joint 24,800 + 1,300 for each 65 and over or blind
Married filing Separate 12,400 + 1,300 for 65 and over or blind
