Settings: Channels
Settings no longer has a Channels page. Each channel is an app now: open Settings › Apps and choose Telegram, WhatsApp, Discord, Slack or Text messages (SMS); the Communication category lists them together. On the app's page the channel is a Built in way to connect, and Set up (or Open once it is set up) opens that one channel's own settings: its connect steps, Start and Stop, pairing, and paired accounts.
Read Settings: Apps and Channels.
Old Channels links open the matching app in Row-Bot, or the Communication apps when they named no channel.