[LordHeini]

Trumpets usually have tuning slides which are actuaded during play. Usually the tone is too high on specific button combinations in certain registers. On those the player moves the slide out a little. It's really a no brainer for the most part.

Alternatively you can give them additional valves which are tuned slightly differently. Which is usually found on Tubas and other deeper brass instruments.

There are more technical solutions like compensator valves too.