Leaf curl can be caused by a number of things such as over watering (is the soil damp/soggy to the touch) or under watering is the soil dry to the touch), being root-bound (is the plant too small for its pot?), etc. Also - is this pot indoors or outdoors? If outdoors, is it possible it got injured by cold weather? Another possibility for leaf curl is herbicide injury caused by drift from any spraying that may have been done nearby.
Curled leaves can be a sign of an insect invasion. Inspect your camellia for any signs of insects. One possible culprit are aphids which suck juices from leaves which then curl and become distorted. More information on aphids and recommended treatments can be found here: https://www.gardeningknowhow.com/plant-problems/pests/insects/homemade-aphid-control.htm
I hope that helps.