In Texas, a police officer cannot enforce a child custody order. The officer can, however, help the custodial parent to enforce the order by providing transportation for the child to the custodial parent, or by providing protection from the non-custodial parent, if necessary.
If the custodial parent is not able to enforce the child custody order on their own, they may need to file a contempt of court action against the non-custodial parent. A judge can then order the non-custodial parent to comply with the child custody order, and can impose penalties if they do not.