Sealant needed before painting?

I am getting ready to paint an Adirondack chair that is raw wood and will be placed on an outside covered deck = exposed to weather but not in open direct rain or direct sunshine. The client lives a mile from the beach, low to moderate humidity.

The client requested a chippy layered look with some wood peeking thru the layers of various colors. I am very experienced with this technique; however, I have never done it on a piece that will be placed outside. I will be using exterior paints and an exterior protectant for the sealer.

I have these questions:

Since they want some wood peeking thru, and the wood has never been stained or painted or sealed would it be smart to seal the wood first with some type of clear protectant? If "yes" what type? OR will the final exterior protectant be enough/meaning do nothing before adding layers of paint and then add final exterior protectant.

Thank you!