Quickly view the monthly/yearly calendar
Open Terminal and type command cal. What you get is calendar of current month, e.g.
   November 2020      
Su Mo Tu We Th Fr Sa  
 1  2  3  4  5  6  7  
 8  9 10 11 12 13 14  
15 16 17 18 19 20 21  
22 23 24 25 26 27 28  
29 30               

You can choose to display whole year, for example cal 2021. For more options open calendar manual by typing command man cal.
This solution is available on all versions of MacOS (and Linux). Another advantage is you can copy and paste calendar as text to other apps.