Patterns like engulfing candles can be used as a signal to enter a trade. But to increase your probabilities you should use them in combination with other things such as support/resistance, and the most important: price structure.
For example, price is in an overall downtrend, but there’s a pullback up to a resistance zone, then a bearish engulfing candle or a pin bar forms.
That’s when you have the best chance of success.