How to set alarm on DS3231 sensor?
Yes it is (see datasheet datasheet) ... the DS3231 has 2 alarms.

There is also a library for the Arduino, see: library.
The alarm(s) can be set (repeatedly) via one of the following functions:

Alarm.alarmRepeat(hours, minutes, seconds, function); 
Create an alarm that will call a function every day at a particular time. 

Alarm.alarmRepeat(dayofweek, hours, minutes, seconds, function); 
Create an alarm that will call a function every week on a specific day at     
a particular time.

 "dayofweek" can be dowSunday, dowMonday, dowTuesday, dowWednesday,
 dowThursday, dowFriday, or dowSaturday. 


Detailed info and more functions: link