Absolutely! If you add a new field, you should be able to tell it to determine the time duration since the date entered into the prior field. JavaScript or Python, depending on your comfort with either language, can perform this function.

We use the online version (odoo.com), I think this cannot be retained. What you think?

Hi,

You can add a compute field in the same model and then subtract the selected date with today's date and then show the days left.

For adding compute field from UI: https://www.youtube.com/watch?v=j981dytxE28

For adding compute field from code: https://www.youtube.com/watch?v=RirBoceNT5Q

Thanks