Length events on more then one track

Is it possible to lenghten notes on track 1 (altosax 1) and add the same length to track 2 and 3?

Are the tracks identical?

Mostly yes. I will export the parts to Dorico after arranging.

You can select all parts and double click, this will open the editor for all 3 in overlay, this way you can select all required notes at once