[SOLVED] There is a cube A and the other is a cube B. I want to achieve an effect. When the displacement value of cube A on the X-axis is consistent with that of cube B, cube B will be doubled in size

this is an error

Welcome to Amory3D.
This cannot work. Connect Out of On update with In of is True and try again. It needs to know when to evaluate the logic condition. Posting the blend file helps getting more answers (and better ones). You can always strip it down to the pure problem. Better is if you learn how to systematically approach solutions yourself: Check the online examples and analyze the interesting ones with the help of some documentation:

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