how did he do it please if there is a tutorial on how to do it
Easy. Get a tripod. Take 2 pictures, one with the person in the frame, one just with the background. Find a brush that makes that neon blue line. Trace the outline of the part of the shirt/jacket that you want to be in neon, then cut out the parts of the layer without the person in it and only leave the parts of the person that you want.(like the shirt inside the hoodie.) then if you know anything about photoshop there might be a little bit of final touching up to make everything look nice but that’s basically it.
TMM10 is right, but I doubt this guy was ever in that setting. If you have a picture of a person and a background you already want to use it wouldn't be that difficult to blend them together for this effect. In this case the only part that appears to match the background is the sunlight on his hair.