Hi,

Open the project module, if the project is linked with the sale order, there is a smart button visible in the form view

click on the button we can see the related sale order from the project module

The view contains the sale order details - which give the overall detail of the sale and we can see the related project and task under this sale order

For more reference, you can refer to the documentation: https://www.odoo.com/documentation/13.0/applications/services/project/advanced/so_to_task.html
or this blog: https://www.cybrosys.com/blog/how-to-create-task-from-sale-order-in-odoo-15-sales-module