how to update my trusted certificate

Hello Prin_ce,

Welcome to Apple Support Communities. For any trusted root certificates on your iPhone, if they need updating the easiest step is to fully update your iOS version. That will ensure the trusted root certificates are also updated.

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

Take care.

You don't need to worry about this if you have the latest update for your iPhone. If you are not sure what that might be, check as follows:

Home Screen > Settings > General > Software Update

If you have a recent version of the iPhone, the most up to date software would be iOS 15.5