If you don't want to be tracked when you are shopping, turn off your smart phone WiFi. Use your mobile data instead if you still want to use the internet, otherwise turn that off too.
Also, when you are browsing the internet, looking for items you might buy, turn on Private Browsing on Apple devices, InPrivate browsing in Windows Edge or Incognito mode on Chromebook. In fact most browsers allow you to browse without being tracked. However, your favourite websites will not recognise you and you will have to log in each time. Once you do that, they know who you are and what you are looking at anyway. But, presumably, you consider that acceptable or else you wouldn't have an account with them. 