What's the standard deduction for two seniors over 65 years old? 1040-SR page 4 implies it would be 33,700, when we add the number of checked boxes for age/blindness.?

Only 30,700

For 2023 the standard deduction amounts are:

Single 13,850 + 1,850 or 65 and over or blind

HOH 20,800 + 1,850 for 65 and over or blind

Joint 27,700+ 1,500 for each 65 and over or blind (both 30,700)

Married filing Separate 13,850 + 1,500 for 65 and over or blind

You are looking at the Standard Deduction for tax year 2024.

The Standard Deduction for 2023 for two seniors age 65 or older and filing as Married Filing Jointly is $30,700

Standard deductions for 2023

Single - $13,850 add $1,850 if age 65 or older
Married Filing Separately - $13,850 add $1,500 if age 65 or older
Married Filing Jointly - $27,700 add $1,500 for each spouse age 65 or older
Head of Household - $20,800 add $1,850 if age 65 or older

However, if you are both age 65 or older and both legally blind the the Standard Deduction would be $33,700.

Oh, are you both blind?  Standard Deduction for Joint is 27,700.  Then you get an extra 1,500 for each spouse over 65 and 1,500 for blind.