Apple's Configurator App enables you to easily manage multiple devices and set policies for them (including security and password requirements). It's a powerful and complex tool, so we recommend reading the official documentation (at the link above) to get familiar with it.
For maximum security you should at least do the following:
- Only use supervised devices. If not, users can override or remove your settings. With supervision turned on you can be confident that your devices remain secure.
- Under Restrictions, set these options:
- Uncheck "Allow screenshots and screen recording".
- It's also a good idea to check "Force encrypted backups" and "Force automatic date and time".
- If you require a long passcode (recommended, see below) you should check "Allow modifying Touch ID fingerprints / Face ID faces".
- Under Passcode, set these options:
- Uncheck "Allow simple value".
- Check "Require alphanumeric value".
- Set "Minimum passcode length" to at least 8. Please note that along with this option you should also allow the user to set Touch ID fingerprints or Face ID faces (see above). If not, the device will become very cumbersome to use.
- Set "Maximum number of failed attempts" to e.g. 10
- Under AirPlay it might be a good idea to whitelist only selected TVs. This prevents malicious AirPlay devices to intercept video and audio.
See screenshots with examples below.