Create ability to move multiple tasks' dates forward the same length of time

Welcome, @Dolores_White1,

You can already do this in a couple of ways in Asana.

One way in Timeline or Gantt views; click+drag to lasso multiple tasks, or Ctrl/Cmd+Click multiple tasks, then move any one of them left or right to move them all relatively.

https://forum.asana.com/t/dependencies-in-timeline-gantt-chart/183844/2?u=lpb

Another: See the Asana help:

Auto shifting dates for dependent tasks

Thanks,

Larry