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.
That was it! Theres a little Add a Control prompt at the bottom after the long press and I found the bell. Thank you. Huge oversight from the dev team, dang.
