I'm not a parent, however, my #1 recommendation for parents is: if the child is autistic, DO NOT listen to the many people who will push ABA (applied behavioral analysis) "therapy" on you. The organizations that push it are very good at making their bullshit look legitimate enough to get pushed by other organizations, including schools, but ABA was invented by the same person who invented gay conversion "therapy", and adult autistic folks who were subjected to it as children overwhelmingly regard it as abuse.

That aside, it's apparently really common for a child's diagnosis to lead to a parent's diagnosis too lol. Especially for parents who don't fit the incredibly specific stereotypes.

For ADHD, I would like to recommend the youtube channel How to ADHD. I don't always agree with it on all points (for example, I think it presents the differences between ADHD subtypes in too gendered of a way), but overall it's a well-researched resource that is good at presenting information in an easily digestible way, and because it's run by a woman with ADHD it avoids most of the issues that are common with resources run by neurotypical doctors and similar.