If you doubt this 2021, not many will start it well since they could run out of WhatsApp in 2021 since the system will not be compatible. Thus they mentioned which will be the operating systems that will no longer be compatible, to continue using WhatsApp you must update your cell to a more recent version. Cell phones in danger are the following:
If your iPhone does not have at least iOS 0 or later versions, they will run out of the App, that is, all iPhone 4 and earlier models.
Models 4S, 5, 5S, 5C, 6 and 6s must update their operating system to iOS 9 or later in order to continue using WhatsApp
Android
The App will stop working if the device has a version prior to Android OS 4.0.3 and later versions, as well as phones with an operating system lower than KaiOS 2.5.1
To know what operating system your cell phone has, it is important that you enter the configuration menu, then in general and there the Software update section will appear where that information appears.