18% ish returns over 10y are impractical for the kind of risk you are quoting. The aftermath of 10y with 15%+ returns is surely a big bubble burst.
If any fund style can give 15%+ over 2024-34 (even for microcaps) that would mean a very low entry base or very high inflationary period or a sudden regulatory change driving all assets towards Equities.
For managed funds, possibility is a very niche manager with smaller AUM who can take agile bets and be extremely lucky. But can't aim tmfor that possibility.
I cannot think of any other scenarios with Equities warranting that high returns.