Using height measurement without flying

In addition to other tasks, I would like to use my Mavic Mini 2 to measure the height. In the DJI Fly app, the altitude is constantly zeroed when you are not flying. Is it possible to read out the altitude sensor in the Litchi app and set a manual zero point while the motors are not running?

For Example: manually zero height → move drone 1 meter up by hand. → App should show me 1m in height, instead of reset to zero.

Many thanks in advance and best regards,

That is not possible with Litchi (nor with DJI software, I suspect). The barometric altitude is zeroed when the drone is powered up and when the drone lands or is held motionless in your hand. There is no option to manually set the zero point at some arbitrary height.