There is such an action "Calculate the difference between the dates of the process, taking into account the coefficient and write it in an additional field of the process"
In it, you can calculate the date difference and write it in an additional field
Then there is this action "Write a date value to an additional process field based on the process date offset"
In it you can apply an offset from an additional field of the process and write to the date (home field with the type date / date and time)
And then such an action "Copy process fields", where you can copy the date from the additional field to the field, for example, "Run until", and then set the action "Switch to stage XXX after the due date"
or
You can set the action "Change the business process and stage depending on the values of the fields", where you will check the date in the additional field
https://prnt.sc/10h5lfw