How do you get a secure WiFi network?

A secure WiFi network will use either WPA2 or WPA3 encryption - this being configured on your WiFi Router and any WiFi Network Extenders that you use.

This support page will describe the more secure (recommended) settings for WiFi:

Recommended settings for Wi-Fi routers and access points – Apple Support

If your devices are running iOS/iPadOS 14.2 or later, you may also be interested in new privacy feature that hides your physical MAC Address - and instead uses a randomly selected Private MAC Address. This feature can be enabled/disabled on your iPhone/iPad for each configured WiFi Network.

More information about this new feature can be found here:

Use private Wi-Fi addresses in iOS 14, iPadOS 14 and watchOS 7 – Apple Support

You should note that these security measures are applicable only to the WiFi network itself - and has no bearing upon the security of your WAN (Broadband) connection. This connection is protected by the transport protocols with which you connect to external services (such as SSL/TLS - and if you use VPN, protocols such as IPSec, IKE, WireGuard etc,).