I can’t understand how this would have any value prior to a harvest. The concept is to probably lower the root zone temperature to help increase the probability of turning the buds a purple color. This process could take about 2 weeks or longer, it cannot happen in a few days.
Any quick trick to try get your plant to apparently produce more resin is normally BS.
Ice flush, 48h of dark is not going to magically make your plant more potent.
Just grow the plant well, that's the best way IMO.