Deductions for job related (W2) expenses have been suspended for tax years 2018--2025.  You can no longer take those deductions. There is no place to enter that information on your return.

Here is a link with more information for tax years before 2018.  

Mileage reimbursed tax-free is never a deduction.  If mileage reimbursement is taxable to you (included in your W-2 box 1 taxable income) you can take a deduction against that income.  That deduction was suspended for W-2 employees for 2018-2025, but the mileage may be deductible on your state tax return if you enter it.  (In most cases, it won't make a difference, unless the mileage is a substantial fraction of your income.). You can enter it on the Deductions and Credits page under "job-related expenses" and it will flow to your state tax return if you are eligible.