If I am using $40,000 in medical tax deductions for 2023. Can I roll over into 2024 tax filing any unused deductions from that? Can I claim less deductions and use later?

For medical expenses, you can only claim the excess over 7.5% of your AGI, as an itemized deduction. There is no carry forward of any unused portion of itemized deductions.

This means that if your itemized deductions are greater than your AGI, then your taxable income will be reduced to 0 and the excess is lost.

Your cannot claim less medical deductions in 2022 and claim the balance in later years.