If you have a chair which is made out of wood, then you can start preparing this chair for survival uses you can get out of , in case of emergency. If you take the the seat off, you can use it as a type of sled to get down hills quickly, or to load something heavy on and slide along the ground. Or someone could pull apart the legs and jam them in the ground and then place something flat on top in order to make a table. With the right kind of chair, the chair back could be cut off and used as a frame for a homemade backpack. If the chair has round dowels they could be removed and used for rolling up a map, or for rolling up string. Or, it might require a few tools, but a person could also remove one of the legs and add the slats from the chair back to one end, making a paddle. The slats could also be used as splints to bind up a wound.
If you have Metal chair then if there is one long tube part bent around from the left back leg to the right back leg, it can be unbent and used as a long pole, possibly for walking or fishing. If the metal seat is a solid piece it can be turned over and used to hold water, or as a tray of some kind. The little plastic foot pieces can be pulled off and used to hold very small items, such as seeds. Any screws, nuts or washers can be removed from the chair to be used elsewhere. On a card table chair that folds up, you could also remove the front legs and put them together on one of the sliding hinges to create a small A frame that opens and closes. This could be used as a bi-pod for steadying a site.
Cloth chairs provide material that can be used for bandages or for cleaning a wound. The cushions can be used as sponges to soak up water where another tool might not work. All depends on the different pieces which can be taken apart and reassembled to make a rough shelter on which to spread a tarp. Whatever the need is, the entire chair should be looked at, and each piece analyzed as to whether it can help or not. Once we stop seeing it as a chair and start seeing all the various pieces, it becomes easier to find alternative uses.
I hope this has been helpful. Nearly everyone has chairs in their homes. So if things go badly, we can always find a chair and adapt it to our needs for the moment.