Some images you see online will be graphic and disturbing, however there is sometimes a need for these images, so they will not always be removed as breach of violation. Examples include:
Animal abuse- often very graphic images are used to raise awareness of animal cruelty, whether domestically or industrially (animal welfare in the food industry). Some of these images do need to be age-gated, and you can find out how to report that here;
Images of war and casualties of war- again images are used to raise awareness and campaigning
Images of self harm- some platforms will move this content but most will not- these images again can be used as part of peoples story and recovery, can also be used by campaigners to raise awareness.