This is one of those things I grew up with and have assumed everyone knows about, but the knowledge doesn't appear to be universal. It is how we pretty much always made tea for iced tea in the desert Southwest.
The process is pretty simple: put some tea bags in a clear jar of water, set out in the sun for a while, and then you have tea. It's sun- and temperature-dependent, but either working separately, or both together, will lead to some degree of success. In other words, a cold sunny day or a warm cloudy day will work, but a cold cloudy one won't be so good. Sun seems to matter. Regardless of temperature, tea seems to turn out better when it's in the sun.
I was surprised to read that some feel sun tea is potentially unsafe. If the bags are contaminated, they could be correct, but that's probably very unlikely (see also below). If the water is contaminated when it goes out into the sun, then having it sit out there warming up for a few hours certainly won't help, but if the water is okay at the outset, the tea bags would be the only thing that could cause problems. In my new house, I was originally on a bored well that had some contamination issues. I didn't make sun tea much back then because of my work schedule. The water I was drinking out of the bored well was a mess generally, with or without making it into tea.
Although I've been doing it for decades, the process I follow is still ad hoc and it's widely tolerant of divergence to the upside: leaving it out for too long does not ruin it. I have a jug that's about 1.5 gallons, and I put three Luzianne family-sized tea bags into it. Four can be used and will make satisfactory tea faster. Lipton or any other kind also work.
Then I just go by sight. On a sunny day in the summer, it can be ready in as soon as a couple of hours. If it's spring or fall and cooler, it might take four. If it is cloudy, it takes longer. As noted above, cloudy days often lead to cloudy tea, but I haven't studied it systematically.
Lipton, Luzianne, and possibly others also have cold brew varieties. I have only seen Luzianne on the shelf. It does work okay, though I let it go for longer than five minutes. It can be put out in the sun and works fine that way, though I haven't tried it when it was warm out, just when it has been below about 50 degrees. It doesn't have to go outside: it can also be made on the counter indoors. The taste is different, but it'll work if nothing else does. And obviously, if sun tea poses a risk, cold-counter tea does, too.
Once tea is made, it lasts through the day and usually is good into the next day--but beyond that is very iffy. Sometimes it's cloudy and getting off flavors the next day, too. Various sites suggest letting it cool at room temperature before refrigerating it to ward off cloudiness. When the weather is cool outside, this won't be as much of an issue, but when it's warm, the water will obviously heat up even if there's cloud cover.
One of the better aspects of tea made this way is that it is cheap: If $3.48 (as of May, 2022) buys 48 family-sized tea bags, and each batch yields 10 glasses, that's only about $0.02 per glass for the tea cost, plus any sweeteners or other flavorings added at the time of drinking. That compares very favorably with any pre- made or mixed tea product. So drink up!