Does the Bible say that children are supposed to take care of their parents when they get old?

There is one verse: 1 Timothy 5:4 But if any widow have children or nephews, let them learn first to shew piety at home, and to requite (repay) their parents: for that is good and acceptable before God.

While it doesn’t say it is a command, like Colossians 3:20 Children, obey your parents, it is something that the Lord finds acceptable and good in His sight!