Approaching the topic about your death with your child will never be easy.
This is even more so if your child is living with some form of physical, sensory, or cognitive-linguistic challenges that makes it difficult for them to understand words in a meaningful manner. This often leads to many parents struggling with their child's atypical reaction to the news and fearing they may not understand it at all when the time of their death comes.
Preparing your child to live a world without you will be hard, rough, stressful, and scary, but not if you have taken the time to prepare them. Just remember, you are not alone in this endeavor.
Below are some websites approaching this kind of conversation and how you can practice steering the conversation in a way that is both helpful and understood by and for your child:
Explaining Death to a Child (includes Sesame clip talking about death)
For parents, there are also social networks that could also help you navigate through this important topic:
Parents Helping Parents - Parenting Neurodivergent Children or Neurodiverse Network