Give Max Verstappen a test in the Racing Bulls car, so he can learn why the RB car is much better to handle for his own team, Red Bull Racing. Not a crazy idea, but there are logical reasons why the Austrians don't do this.
The RB21 from Red Bull Racing is a tough car to control, as Max Verstappen has experienced more than regularly throughout the current season. The Dutchman may look with some envy at the Racing Bulls car, the sister team of Red Bull Racing.
Although the performance peak of this car seems lower than the RB21, the vehicle is easier to handle. It is conceivable that Red Bull Racing would like to know why the car of the smaller team is more pleasant to drive, but it is not allowed to exchange technical data.
What is possible is to have a Red Bull Racing driver do a test in the Racing Bulls car during a film day; every team can do that in principle. Mercedes can allow George Russell to test the McLaren car for a day, to discover the secret of this car.
Only, no one does. Not even Red Bull and Max Verstappen, although the threshold for two teams of the same owner is lower than for McLaren and Mercedes, for example. Why Verstappen has not taken this step seems to be due to a simple fact: Red Bull does not want to annoy the other teams on the grid.
Without a doubt, competitors would scream murder and fire if Verstappen and thereby Red Bull took a look at Racing Bulls kitchen. With his enormous experience and excellent technical knowledge, there is a high chance that Verstappen would discover something that he could benefit from.
The attentive reader might state that Red Bull does allow rookies and inexperienced drivers to participate in free practice sessions; sometimes at Red Bull Racing and other times at Racing Bull. Isn't that the same? In a sense yes, but the inexperienced reserve driver Ayumu Iwasa is probably already busy enough keeping the car on the track - let alone drawing comparisons with the other car.
Moreover, it can be questioned what use it would be for Red Bull at this time in the season to have Verstappen test for the sister team. There will be no more updates at Red Bull Racing and all focus is fully on 2026. Then completely different cars will come on the circuit that may have no problems at all.
In short, the idea of a Verstappen test intrigues. But it is definitely not going to happen.