Had to order a few fenders from Kawasaki in my youth years (don't know why @!#@!#). They always came totally finished in whatever color you ordered. Striping was part of the finished product.
The primer and basecoat was laid down, then the pinstriping applied and clear coat on top of the paint and pinstriping.
in your picture on the left lower side, you can see the overlap of the pinstriping on the stop start and then you can see the slight thinning of the stripe going in to and coming out of the corners caused by the stretching required to "make it around the corner". Your example in the picture is pretty damned good and was done by a really good pinstriper.
You can find pinstriping tape at most graphics outlets or order on line. Sometimes striping doesn't come in the exact color you want and a good graphics outlet can match vinyl to your sample and cut you stripes from a roll of vinyl. I had this done to match striping for the CBX. It then came in 8 ft lengths.
Multi stripes like on the Kaw with a narrow stripe and a fatter stripe can be bought that way and comes with a clear stripe over top of the 2 stripes to hold the stripes parallel during application. Once laid down, the top clear stripe is removed by peeling parallel to the stripe. After striping, a clear coat is applied
Check out this site as an example of a supplier.
This example was recently advertised for sale down here as being an original OEM finished product - it has 4 x pieces (or joins), I am just trying to verify that, 40 years ago, thats how they left the factory...