My sons turned 27 and I paid insurance premiums for them. Where do I deduct these premiums including medicare?

You can include medical and dental bills you paid in 2021 for anyone who was one of the following
either when the services were provided or when you paid for them.
• Yourself and your spouse.

• Any person you could have claimed as a dependent on your return except that person received $4,300 or more of gross income or filed a joint return.  as a qualifying relative, you would have had to provide more than 1/2 of his support to claim him as a dependent.

the expenses are reported on schedule A under medical expenses.

Are you claiming your sons on your taxes?  If you are, then you can claim any medical expenses you paid for your sons.  

If you are not claiming your sons on your taxes, you can claim medical expenses you paid for a qualifying relative are deductible if you paid them to prevent or treat a medical or dental problem. You can include all expenses that you actually paid during the year, even if your relative received the care during a different tax year.

Publication 502 Medical and Dental Expenses