The short answer
Yes. The green horse-drawn calèches gather near Jemaa el-Fnaa and the Koutoubia, and a loop of the ramparts is a relaxed, low-effort way to see the city without tired legs. Agree the route, time and total price before you set off, and choose a carriage whose horse looks healthy and well cared for.
In more detail
Children tend to enjoy the novelty, and anyone wanting a rest from walking can still cover ground. A favourite route follows the ochre ramparts past the historic gates; others head out along the broad, palm-lined avenues towards the Menara and Agdal gardens area. Sitting back in an open carriage is an easy break from the heat and the crowds.
Marrakech runs an official tariff system for calèches, with posted rates and zones. Even so, agree the route, the duration and the total price with the driver before the carriage moves, and ask whether the price is per carriage or per person. If the answer is vague, walk to the next carriage.
Horse welfare is part of the choice. Pick a horse that looks healthy, with a reasonable body weight and no obvious sores, use the official ranks, avoid the midday heat and do not overload the carriage. If a horse looks mistreated, you can decline it.
Getting into a carriage means a step up, so ask the driver for a hand if you need one. Ranks are near Jemaa el-Fnaa, the Koutoubia and some larger hotels.