It is actually easier to use dependencies since Airtable tables do not have an inherent row order and without them, your formula would need to find the previous task based on some value.
To set up dependencies, create a linked record field linking to the same table it's created in. I suggest deciding if you want this field to hold predecessors or successors and name it as such. Now you can get the dependent task's due date through a lookup field on this linked record.
It's probably best to manually enter task dates at this point than rely on a formula field as these will inevitability change. A useful automation here might be to insert the dependent task's date + conditional number of days based on day of the week when the dependent task is updated but automations can also make your base confusing to fellow collaborators.
Another tip: you can use the Gantt View to bump up or down dependent task dates simply by dragging and dropping the ends of task periods, making mid-project task management much easier (and another reason why I would suggest setting up task dependencies).
Hope that is helpful!
