Am connected to a strong wifi hotspot but can’t find download and install option,can’t update help me

Some more things to check

•  you are on a good Wi-Fi, (from 15.4 iPhone 7 up, you may be offered cellular update) but not another iPhone personal hotspot
• Plenty of spare storage – 6GB at least.
• on charge with more than 20%, OR 
• off charge with more than 50%
•  low power mode turned off. 
• Check Settings, General to make sure you have no Beta profile installed.
• no VPN installed (Check Settings, General, VPN & Device Management)
• You have iphone 6S or later

Ask Apple if you think my answer is not helpful, we are users like you.

You can reach out to Apple Support directly. You should be able to reach them here

Contact - Official Apple Support

or phone numbers

Contact Apple for support and service - Apple Support