A cat that sleeps stretched out needs enough continuous supported space for its preferred posture. The answer therefore depends on the flower bed's usable centre, not just the total width across the petals.
Measure the length and width your cat occupies while relaxed on a familiar surface, then compare those measurements with the bed's internal shape. A round centre may suit curling better than a long, narrow sleeping position. Soft edges can be comfortable, but they should not be counted as supported extensions unless the manufacturer explains that they are intended for that purpose. Consider another broad platform or floor-level bed if the flower centre looks restrictive. You can still choose a flower design for climbing or short rests, provided the cat also has a genuinely spacious option for longer sleep.
Use a paper rectangle matching your cat's relaxed outline as a visual aid when comparing a round centre. A rectangle's corners falling outside the circle show why equal maximum widths do not necessarily provide equal supported space.
For product comparisons alongside this advice, see Floral Canopy and Arbor Retreat. The details below explain their sizes and uses.
Further reading: cats.org.uk; cats.org.uk.
Floral Canopy
Arbor Retreat
Linden wooden cat tower