Most are set to beep at 3.5v per cell. You usually want to land before that point. When it’s 200ft up and flying fairly fast you can’t always hear the beeper.
A cell checker and balancer is more useful than an alarm. You use the timer on your TX (or phone if the TX hasn’t got a timer) for planes. I fly my first pack for 4 mins, land, check the battery charge level and cell voltage with the meter, then do another minute. Rinse and repeat until you hit about 3.65-3.7v per cell and no lower than 35% charge. Set timer for 1min less than that. Then you have some capacity spare and don’t pound your lipo.
I use Hobbywing ESC’s, they come pre set to drop to 50% throttle at 3.5v so you can never get the lipo to below that without trying really hard.