I see what looks like snow scale on the leaves. and the brown patches look like it may be a secondary infection. How hot has it been? If you do not have a heat resistant tomato it may have some physiological leaf curl. It is also in what looks to be a fabric pot which can dry out very fast so double pot it to slow down the evaporation. Mulching may help as well. Check the soil a couple of times a day. It may need more watering. If you live where it is really hot, consider moving the pot to a place that gets shade in the afternoon or keeping the plant under 35% shade cloth. Cut off the leaves with the scale and the brown spots. Carefully bag and dispose of them in the trash. Check the other leaves for pests. Identify and treat them if appropriate.
Try not to water overhead, especially late in the day. Bacterial and fungal diseases need to be controlled early or use preventive fungicides. If bacterial and fungal diseases are a common problem, consider looking for a resistant variety.
If it gets extremely hot in your area, consider choosing a site with afternoon shade, shade cloth, and choosing a heat resistant variety that is suitable for your area. Plant earlier or later if you can to avoid having to grow tomatoes through the hottest months of the year.
Try growing tomatoes bred for the South and for heat like Arkansas Traveller, Super Sioux, Creole, Cherokee Purple, Heatmaster II, Big Beef, Bella Rosa, Homestead 24, cherry tomatoes., and the heat resistant tomatoes developed in Florida Solar fire, Florida 91, and Sun Chaser.
It would help if you edited your user profile to include your location and zone.
https://ipm.ucanr.edu/PMG/PESTNOTES/pn7408.html
https://hgic.clemson.edu/factsheet/toma ... disorders/
https://www.vegetables.cornell.edu/pest ... varieties/
https://bonnieplants.com/blogs/garden-f ... t-weather/