Sickle cell trait (SCT) isn’t a disease. If you have SCT, you have inherited the sickle cell gene from only one parent. People with SCT don’t have symptoms of SCD and typically live a "normal" life.
Cannabis is likely just as safe for people with SCT as it is for the general population. Cannabis does carry risks. It can cause changes in perception and increased heart rate and may also impair your memory. Smoking cannabis may cause chronic cough and other toxic lung effects over time.