I didn't know if it would make it to narrow?

I wouldn't worry about making something look too narrow. Instead, I'd think about installation. If you do it crosswise, will you end up wasting a lot of material with short ends? If you do it lengthwise, will you have a tricky board to saw in half lengthwise to make the width fit?

What @millworkman said, your porch ceiling joists run perpendicular to the house, you want your T&G ceiling to run perpendicular to your ceiling joists as you would install hardwood flooring.

@sigrid good thought I'll measure it out thank you.

Thanks everyone