Trick to OR Operator

It may be a tiny performance hit, but if you're looking for quick testing you could put the valid strings into a list or array, and check if the array contains the value being tested.

For example, a simple filter might look like this:

 public void SomeFunction()
 {
     string result = PlayerPrefs.GetString("MyStringValue");
     List<string> goodResults = new List<string>()
         {"good", "better", "best"};
     
     if (goodResults.Contains(result)) 
     {
          // do good stuff   
     }
 
     // optionally check other lists.
 }
 
 

At the very least, I would cache the result of the player refs getter to save yourself some keystrokes and lookups, by storing it in a local variable like above with 'result' (though ideally more appropriately named).

[Edit]: If things start to get complicated you may want to also consider using a switch statement. You can fall through cases if they are left blank, allowing you to use it like a chained if / or series, as well as else-ifs.

     switch(mystring)
     {
         case "optionA":
         case "optionB":
         case "optionC":
             //do stuff if == optionA, optionB, or optionC
             break;
         case "optionD":
         case "optionE":
             // do stuff if == optionD or optionE
             break;
         case "optionF":
             // do stuff if == optionF
             break;
         default: 
              // do stuff if none of the above
              break;
     }