There is talk on social media about a security update. I just purchased my iPhone 12. How do I get the link for the update?

Click on this link to read how to "Update your iPhone, iPad, or iPod touch" --> https://support.apple.com/HT204204

If there's one for you it should say there's one. Usually my phone also displays a red circle next to settings to remind me.

There is a recently released iOS update (14.4).