If you already subscribe to Apple iCloud+ for 99 cents a month, this is the easiest route.
From the impacted iPhone, go to....
Settings --> Click on the box at the top with your name --> iCloud --> Private Relay (Beta) --> Toggle it to "On"
The Free Way:
1) Open Safari (not chrome) on your iPhone
2) Go to www.securly.com/ssl
3) Click on "Download Certificate"
4) When it asks for permission to "download a configuration profile," tap "Allow"
5) If it asks to "Choose a Device," choose iPhone
6) Go to the Settings app and go to General --> About --> Certificate Trust Settings
7) There should be a field that says "Enable Full Trust for Root Certificates" with an option under it for *.securly.com. Toggle the setting to ON. When prompted with a Root Certificate warning, click Continue.
8) If you still experience issues after this, you may need to navigate to launchpad.classlink.com/maryville, sign in, and click on the securly staff login icon. It will tell you you need to install the extension. This isn't possible on the iPhone, so just say "Contnue to website" and continue. It will bring you to a Microsoft login page. Login, choose "remember me," and if it works correctly, Wikipedia should load.