Whenever a stock market will be crashing you will smell it before with the help of price action.
whenever crash will happen price will slowly will loose its strength which is clear sign of reversal.
In 2020 when market is crashed it is preparing for itself since 2018 and in 2019 it has given breakdown and pullback in 2020 and then crash happened so their is nothing which is secret everyone can understand it easily with help of charts.
Also after when one rise will come don’t buy in that wait for the price to retrace again it will come down and then plan your entry no need to catch knife unless you don’t want lose Red Colour.