Sure…welcome to the Community. :-)
That’s a pretty easy one. You can use the Find All in Current Document feature:
Invoke the Find feature (press Ctrl+f)
Find what zone: \b....e\b
Set Match case to your pleasure
Search mode: Regular expression
Action: Press Find All in Current Document button
Each . in the Find what zone represents a character position where you don’t care about what value it takes on (your “underscores”). The \b at the start and end just means to encase what comes between as a word, thus the example above would match “whale” but not the whale part of “whales” or “whaleboat”.
This is rather basic “regular expression” stuff so I encourage you to go off and do some reading about what that is and how to use it for your needs in the future.