I already did the following but in the 90s and it was sort of the reverse. You used something to cover the area you wanted the ‘tantoo’ so you would get a tan and that one spot would remain ‘white’ say a heart shape for instance.
Now these idiots are doing it in an unsafe manner by getting burned in some cases. You can use sunblock. You will still get color.
Sadly today even if I wanted to do this I wouldn’t be able to as there’s no sun out. A sucky 4th of July weather wise.