It is possible that when you connect the iPhone, iPad or iPod Touch after a long time without doing it on your Mac, it will show you a software update to continue working normally. In principle it is also possible that your iPhone, iPad or iPad Touch is currently with the latest available version of the software so it may seem somewhat strange, but don't worry. it is common for users running macOS 10.11 or later.
If you see the message "It is necessary to update the software to connect with your iOS device" on the iPhone, iPad or iPod touch, it is because the Mac software is not ready to recognize the iOS device. Nowadays it is common not to have to connect the iPhone or iPad to the Mac at all, but those who want to do so may see this update message.
Once the equipment is installed and updated, this message will no longer appear on our Mac when we connect our iOS devices. In any case, it is important to update in order to continue working normally on this equipment. This typically occurs when the iPhone, iPad, or iPod touch have a newer version of iOS than the one supported by the Mac. It is not something that happens to all users but it sure happens to all those who have a Mac that does not support the latest versions of software released after macOS Catalina.
Once updated the message no longer appears the following occasions we connect the iPhone, iPad or iPod touch to the Mac.