On the timeline, tap the plus on today's date and choose Calm. The Calm editor opens, titled Calm for today, with two cards stacked vertically — one for Meditation, one for Breathwork. Both start empty, each with a + on the right.
If you've already created a Calm entry today, tapping plus again opens the same one in edit mode — you don't end up with two cards on the same day.
Calm editor with empty Breathwork card