Are there any guide lines or simple unwritten rules that men can passively announce they are single in everyday activities?

So, in detail. I am 41M (irrelevant but maybe not). Single. If I am in an area that I don't live, like a city over and I am available, is there anything a guy can do, or wear that says " Hey, I am single, you can approach me." ?

Seems like there should be.

I can not remember where I first saw this, it may have been a practiced thing in Japan where men and women would wear colored wrist bands to declare if they are single, into open relationships, already committed, yadda yadda.

And it feels like this is a real stupid question to ask since normally no wedding ring used to mean, I am single but that was like, 1000 years ago. Today, it is almost a need to passively announce your availability. (Even unfriendly dogs get colored leashes to tell others if they are a friendly animal or not).

That's all I have to ask.