If you need to move a project to a specific date (start or end date) before or after its original date, you can move all the tasks at once.
Project > « Settings » icon, go to the « Project » section:
The field is automatically completed with the start date of the first project task and the end date of the last project task.
If you change the start date or the end date of the project, it will then be moved and it will keep the sequence of tasks.