Can I set up my iPhone to sound an alarm on another iPhone?

Are you talking about Lost iPhone Alarm using Find my iPhone

 Play a sound for two minutes at full volume (even if your device is set to silent)

Locate a device

1. On iPhone or another iOS device, open Find My iPhone.
2. Or on a computer, go to the Find My iPhone web app on iCloud.
3. Sign in with your Apple ID, then select the device you want to locate.

1. Tap Actions, then tap any of the following:

• • Play Sound: Play a sound at full volume for 2 minutes, even if the ringer is set to silent.

1. Ask Siri. Say something like: “Help me find my iPad” or “Play a sound on my iPod touch.” Learn how to ask Siri.

Use Find My iPhone to locate your device - Apple Support

https://support.apple.com/guide/iphone/find-my-iphone-iph09b087eda/ios