Short answer
You How do you turn a volatility forecast into a trade filter by turning the idea into a repeatable decision rule, attaching realistic turnover and risk constraints, and checking whether the workflow still holds up once the flattering assumptions are removed.
In volatility forecasting and dispersion, the useful version of this workflow is the one that survives a clear benchmark, realistic execution assumptions, and a portfolio context that does not quietly change the rules after the backtest is done.