I wanted to buy a b550 bazooka msi mother board but I need to update bios because I have a ryzen 7 5800x,if I buy the board here can they update the bios for me ? Will they be a fee also ?

You can go to the Micro Center Website and schedule to get your bios updated for around $30 or so. Though you could also sign up for AMD’s Boot Kit which AMD sends you a cpu to loan so you can update your bios and all you have to do is send it back, as far as I know the Boot Kit is free.

I suggest call them before dropping by

Give them a call od stop in. If they can't help they will send you in the right direction.