Yes, if you make a deductible contribution to a traditional IRA it will reduce your taxable income by the amount of the IRA contribution. You have to be eligible to make a deductible contribution of the amount that you want.
In some cases the limit on the amount that you can deduct could be affected by things that happen during the remainder of the year. Because of that possibility, you should wait until the end of the year to make your IRA contribution. You can make a 2022 IRA contribution up until April 15, 2023.
IMPORTANT: Note that the zero tax rate for long-term capital gains applies if your total taxable income, including the long-term capital gain, is $41,675 or less (for 2022, filing as single or married filing separately).
