Check what’s standard in your country, I guess. I’ve seen kneeling as the standard posture for the final blessing in at least one parish in mine, so I guess it goes by local custom to some degree.
I have seen people kneel for the final blessing in some traditional novus ordo parishes. I myself have done this. However, I don’t this is proper within the context of the Pauline Mass and so I don’t do it regularly. I do occasionally kneel if the blessing is given outside of Mass.
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