Is it stealing if I paint a photograph that isn’t mine?

I had this really good idea for an art competition but the idea needed a portrait with lights of interesting and colorful lightings. I wasn’t sure how to start forming the whole idea onto a blank canvas so I started searching on pinterest. I found this amazing photo that matched my idea perfectly and was thinking about painting this for the submission. If I were to try and make the painting as similar to the photo as possible and did not make any additions, would this be copying/stealing (btw, I can’t make my own image because i dont have resources and I’m not advanced enough to draw realistic people from scratch).