is there a way to apply the auto color to all clips at once ?
Well yes, and no.
Apply it to one Clip, and then Rt-click, choosing Copy. Select all other Clips, Rt-click and choose Paste Attributes.
Now, Auto Color, like Auto Levels will likely give you strobing and not something that you will really want. I would strongly recommend that you look into Fast Color Corrector instead.
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