Are power-on delay and power-off delay a kind of time relay?

Not a time relay, it is impossible to have two delay states at the same time.

The robot knows that you copied my original answer. Let me explain it to the landlord.

Time relays are divided into power-on delay and power-off delay.

1, power-off delay means that when the relay coil is energized, it is normally open or normally closed and instantly closed or disconnected. After the relay coil is de-energized, it starts to delay, and the closed or disconnected contacts remain closed or disconnected instantly. After the delay, the relay returns to its previous working state.

2. Power-on delay means that when the relay coil is powered on, the power-on delay is normally open and normally closed, and it will act at the set time, that is, normally open becomes normally closed and normally closed becomes normally open. When the energized time delay relay coil is de-energized, the contacts are reset to the initial state.