Hello!

That is not possible out of the box. You might be able to develop something with Studio, but that would still require Python coding. Another solution (if you on-premise or on .sh), could be trying to use a third party app such as: https://apps.odoo.com/apps/modules/13.0/project_task_dependency/.

I hope I helped :)

Have a great day!

Cheers,

Odoo eLearning team.

You could try out our solution for this question, it handles constraints between tasks.

https://apps.odoo.com/apps/modules/14.0/bryntum_gantt/