Can I still deduct mileage if job related I'm an outside sales person and do not get reimbust

If you are a W-2 employee, unfortunately, no, the new tax law effective 1/1/2018 eliminated the unreimbursed employee expenses. If you are an independent contractor, then yes you can.  

I am a commissioned only based employee.  I have read that if I work out of my home and go only to clients that I could still write off mileage.  Is that true?

Only if your W-2 box 13 is marked  Statutory Employee so the expenses can be reported on a Sch C ... otherwise it is a no go.