In my jurisdiction I think that's only partially true.

Firstly, it's also true here that the outcome needs to be "in the best interest of the child", and that's critical.

However, it's not only cases where the child's parents have had a relationship breakdown, but is applicable to cases where the child's parents are estranged from the grandparents:

Sometimes grandparents are prevented from having a relationship with their grandchildren. This can happen where the relationship with their own child has broken down (but the parents’ relationship remains intact), or where the parents have separated and one parent refuses to let them see their grandchildren. Grandparents do not have an automatic right to have a relationship with a grandchild. However, grandparents, and anyone who has an ongoing relationship with the child, or any other person who can show that they are concerned with the care, welfare or development of a child (including grandparents) can apply to the court for parenting orders.

https://www.legalaid.wa.gov.au/sites/default/files/inline-files/Grandparents_family_law.PDF

So it's not a law that would regularly enable grandparents to corrupt children against the wishes of the child's parents.

Additionally, I suspect that parenting orders may be able to require supervised access, or restrict them from participating in religious ceremonies and that kind of thing.