Do Faraday Bags work?

Hi all! I don't usually post or comment anything but I have a question. I saw a video on Youtube claiming that a small Faraday bag for my phone can block all signals, tracking and radiation from it, does anyone know more? Should I buy one or is there a better DIY method? Sorry for my ignorance. Thanks

block can diy don faraday faraday bag phone privacy question radiation signals tracking video work youtube