When a bullish order block turns into a bearish order block or a bearish order block turns into a bullish we call this a breaker block. You can compare this concept to the support turn into resistance, it only uses a different concept, but the same principle. The SMC Indicator offers a setting where you can plot breaker blocks, so you can identify them more easily. Below this there is an image that shows this feature in live action (blue box).
To enable the feature simply head over to the indicator settings.
When you are inside the SMC settings - locate the "Order Block (OB)" section and make sure to click on the Order Block Style dropdown and enable the Breaker Blocks. Voila.