Pretty much the same as above.
Our twins had driven from Brisbane to Cairns and back twice and Brisbane to Sydney before their second birthday.
Now at 8 years old they easily do 4 or 5 hour trips without getting out of the car.
As babies it was all about feed time, we just allowed an extra couple of hours on each days driving for stops.
We tried one ~2,000km trip to break it up over several days, but as above they just got over it. We found it much better to do the 900 odd km each day and just accept that the extra stops throughout the day.
As they get older it’s all about keeping them entertained.
One of the best setups for our kids is to hang there blankies over the windows (close the door with the edge of the blanket in the door seal), then pack the pillows around them with all of their toys at arms reach and no gaps for their favorite toy to fall down into
We found if they picked all the toys they want to bring, they tend to create their own games for them.
We avoid books and tablets as much as possible. Saves the car sickness...
Though DaveR made a good comment a little while ago about having the tablet/dvd player mounted up higher, so the little ones look ahead, rather then down into their laps. Apparently that made a huge difference for his young fella.
The only other tip I have is to talk about the drive before you go. Make sure they fully understand that they will be sitting in the car for X amount of hours. The “are we there yet” conversation is much less painful if they are fully aware of the driving plan for the day/s.