If you read the text in gray below "Learn More" you'll see your problem.
Your iPhone doesn't have enough storage to update to iOS 15.5. Please read the following support page for help managing the storage on your local device: How to check the storage on your iPhone, iPad, and iPod touch - Apple Support.
I hope this answers your question.
Your phone storage is full.... I had this happen with my moms iphone 6s and the only thing that helped is updating the iphone via a pc or mac
See this link on how to update your iphone via a Mac running macOS Catalina or later Update your iPhone, iPad or iPod touch with the Finder – Apple Support (UK)
See this link on how to update on a mac running macOS Mojave or earlier or on a windows pc
Update your iPhone, iPad or iPod touch with iTunes – Apple Support (UK)
Maybe because you need to use a good WiFi Internet connection to install the update and you can't install the update using a cellular connection.......and......you don't have enough free space on the iPhone to handle the installation.
The explanation about lack of space is right there in front of you.
i have gone in the settings as i’ve been directed but nothing is there showing that i install it only stops on directions why 🤷♀️🤷♀️
