How to sort tasks by level of complexity x volume of work?

Hello everyone! Thanks in advance for your time.

I made a table to log tasks, where I put one column for level of complexity (S-small, M-medium, L-large) and another column for volume of work (S-small, M-mediu, L-large). Another third column sums it into SM, SL, SS, MM, LL etc and also sorts it by a custom order.

How can I make a formula for one more column for URGENCE LEVEL, where I can put a formula that says like IF Hierarchy = SS, SM or SL then show the word “HIGH”, then IF Hierarchy = MM or ML, show the word “MODERATE” and IF Hierarchy = LL, then show “LOW”.

Idk, it seems simple, but I advance I am a creative that managed into adulthood without learning many formulas, god only knows how. So after failing the whole afternoon I came to look for your wisdom. Thank you guys for reading me! :smiley:

   "SS", "HIGH", 
   "SM", "HIGH", 
   "SL", "HIGH", 
   "MM", "MODERATE", 
   "ML", "MODERATE",