Yes bleach can be poured down the toilet.
I use bleach in my toilet every few days to help keep it clean and help disinfect the toilet.
I clean my toilet as needed with toilet bowl cleaner but also I often scrub the toilet bowl down inside with bleach to kill germs and viruses and bacteria.
The bleach is a great disinfectant that kills germs, viruses and bacteria and works great to keep your toilet clean.
Just be sure to never mix ammonia with bleach because it creates a deadly gas and be sure to ventilate the bathroom or any room you're using bleach in.
The bleach smell can make you sick if you do not have ventilation.