How to change security WiFi setting to WPA2 (AES) or WPA3

Your router's manual should show how to change security settings. You can also search the internet for instructions for your particular make and model router. An older model may not have the current security settings, in which case, you may need a new router. The router may be included with your internet device. If this is the case, contact your internet provider.

That’s a setting made in your WiFi Access Point / Router.

Your iPhone merely “follows.”