This is going to be more of a sensory session.
In the form of a bath or shower with some essential oils or just soaps/ foams/gels/salts your child enjoys the smell of. You could provide a choice of two or three. Roughly citrusy smells are uplifting and activation where lavender chamomile and baby sleep time washes relax. But feel free to use what suits your moment. In corporate a bit of gentle stretching afterwards of the areas your physiotherapist has recommended.
If your child has no physiotherapist a scented bath can still be a great way to get some chill time in the day or before bedtime.