We know smaller canyons can be cut in days. For example in Texas a mile long, 100's of yard wide and 50 foot deep canyon was carved in 3 days which was exposed in 2002 when extensive flooding of the
Guadalupe River led to a huge amount of water going over the
spillway from
Canyon Lake reservoir and removing the sediment from the gorge.
Canyon Lake Gorge - Wikipedia
However that is not evidence a great flood covered earth and cut the grand canyon. If I remember correctly the great flood rose in 40 days and drained in over a year. Covering the highest mountain(MT Everest is 29,029 feet). Water rising that fast(29,029÷40=725 feet per day) wouldn't carve the grand canyon and water receding down slowly (29,029÷365=79 feet per day) wouldn't carve the grand canyon. Of course that's my opinion.