Why is there no option to manually update my iPhone software. The latest update hasn’t downloaded in the last 3 nights.

To manually update the iOS on your iPhone, go to Settings>General>Software Update. When you do that, it will automatically check to see if there is an update, and it will prompt you to download and install. Make sure the iPhone is at least 50% charged, connected to power and to a stable wi-fi network. If that is not working, then come back and explain your problems, starting with what version of iPhone you have and what is the current iOS you have. The most current iOS is 15.4.1.

Automatic update should still work if your phone meets all of these requirements:

• You need at least 6 GB of free storage
• You must be connected to a Wi-Fi network (and not a personal hotspot) unless it is an iPhone 12 or 13 series with an active 5G network connection
• The phone must be plugged in for automatic updates
• The screen must be locked for automatic updates
• The phone must not be in Low Power Mode
• The phone must not be connected through VPN, and it may be necessary to delete any VPN apps and VPN profiles
• The phone cannot be in Airplane mode
• You cannot still have a beta version installed on the phone

What does it say in settings - general - software update?

Now I find there was a misunderstanding about your issue. You were referring to a Watch update, not an iPhone update. It seems you were having issues with an Apple Watch update which is handled differently. The iPhone needs to be connected to power and wi-fi to download the Watch update to the iPhone. Then, you should get an Install button on the iPhone. But before pressing that, the Watch needs to be at least 50% charged and connected to the charger, and near the iPhone. Then you can click on Install and it should download to the Watch and Install.

Now you are bringing up the Apple Watch. That has nothing to do with the iPhone updating. Can you provide a screenshot of the actual screen you are seeing on your iPhone? That may make it a little easier to determine what the problem is and how to fix it.