Not in real-life terms, but for a kid, a larger interest rate will be less slow and boring than a realistic one, and it will be more engaging.

“The first national bank of dad” is a book that suggests a similar approach and I believe it also advocates a 15% interest rate.

I remember watching the statements for my savings account as a kid and getting like 2¢ of interest per statement and thinking… that’s it?? Why bother??