If you claimed your child in 2018 and not in 2019 and their working will they receive a stimulus check

Yes, the IRS will use the information provided on your most recent tax return. Since you filed a 2019 return that is the return they will use to determine eligibility.

depend how they file their returns for 2019 .  did they check they could be claimed on their own return  - if yes no check, if no they get check

by the way the rule is not whther they "ARE" claimed but whether they "CAN" be claimed even if they are not.