When should you change the spark plugs, transmission fluid and timing belt?

Hello, I see spark plugs are to be replaced by 120,000 miles. I do not see a transmission fluid interval; perhaps under normal conditions changing is not needed. Lastly, this vehicle's engine has a timing chain, not a belt, and is not in need of any maintenance.

I have a 2017 Prius prime premium model original owner. Since I have this car when it was only 12 miles on the odometer till now at 240,773 miles. Only things done to it Full service oil change every 22K to 25K miles Fuilds for coolant still pink Still on original plugs Replaced 5 windshields And replace five sets of tires Suspension is great still