The Time Timer is what you’re looking for!
https://www.amazon.com/gp/product/B001UAMZCU/ref=as_li_tl?ie=UTF8&tag=nhm00-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B001UAMZCU&linkId=4634aa1778e4d16b9480066bc784a47b
There are also apps to make a visual schedule — if you want to show checklists with pictures and have your child check them off as they go. Brili is one:
Penny
ADDitude Community Moderator, Parenting ADHD Trainer & Author, Mom to teen w/ ADHD, LDs, and autism