can I deduct business use of a personal car used for travel to clients

If you are self-employed you enter mileage etc on your Schedule C with your other business expenses.

W-2 employees cannot deduct job-related expenses on a federal return.  Job-related expenses were eliminated as a federal deduction for W-2 employees by the tax laws that changed for 2018 and beyond.  Your state tax laws might be different in AL, AR, CA, HI, MN, NY or PA.

If you live in a state that lets you deduct job-related expenses, the information will flow from your federal return  to the state return, so enter it in Federal>Deductions and Credits>Employment Expenses>Job-Related Expenses

You can deduct these miles only if you are a self-employed attorney. 

If you are an employee who receives a W-2 these expenses aren't deductible on your federal return.   However, you can still enter them in TurboTax under Job-related expenses as they may be deductible in your state.