Why is my phone still not showing where I will click to download and install the new iOS

Update your iPhone, iPad, or iPod touch - Apple Support

Are you:

1. Connected to WiFi?
2. Not using a VPN?
3. Have a 50% battery charge or better and preferably connected to power.
4. Not in Low Power mode?
5. Have 6GB or more free space?

Connected my iPhone to my iMac but does it not show in my iMac Finder