SCID:
https://www.chessprogramming.org/SCID
Chessbase 15:
https://en.chessbase.com/post/getting-the-most-out-of-chessbase-15-a-step-by-step-guide-11-database-search-basics
Click the links to the other guides and how-to to see the other features of CB15.
Finally this:
https://en.chessbase.com/post/ultimate-chessbase-and-mega-database-guide
What is the the difference between the costly chessbase15 and the free Scid ?? Are there any features more in chessbase15 than Scid??