Oh good point sorry. If you open the Control Center (drag down from the top left, typically), there should be a bell icon..?

That, or Settings -> Sounds & Haptics -> Silent Mode ?

I just got an iPhone 17, and presumably because it inherited its Control Centre configuration from the 13 it replaces (which had a physical switch) the silent mode toggle was not present. Tap and hold in an empty space to edit the controls and add it in.