for the 65 or blind deduction adder, do you both have to be 65 if filing jointly or can one of you be younger?

It can by you or your spouse or it can be both age 65 or older

Standard deductions for 2024

Single - $14,600 add $1,950 if age 65 or older
Married Filing Separately - $14,600 add $1,550 if age 65 or older
Married Filing Jointly - $29,200 add $1,550 for each spouse age 65 or older
Head of Household - $21,900 add $1,950 if age 65 or older

It is for each person.  You don’t both have to be over 65 to get the Standard Deduction increase.

Joint is 29,200 +  1,550 for each spouse 65 and over