How to block any app on your iPhone

The short version, for any app

1. Free, with Apple Screen Time. Settings → Screen Time → App Limits → Add Limit → search the app by name → set the allowance → then reopen the limit and turn on Block at End of Limit. For "off after 10pm" instead of a daily budget, use Screen Time → Downtime → Scheduled, and check the app isn't in Always Allowed.
2. Automatic, with Paused. Create a Block Schedule, tick the apps, pick the days and hours, save. They switch themselves off and back on. Need silence right now instead? Start a Focus session and they're locked until the timer ends.

Both use the same Apple Screen Time (Family Controls) engine, so neither one reads your messages, your browsing, or anything inside the apps you block.