I don't think you can do this in a Record Rule, but you could add a filter in an Extension Search View and use that in the Windows Action.

Something like this:

<?xml version="1.0"?>
<xpath expr="//filter[@name='my_sale_orders_filter']" position="after">
  <filter string="Last 4 weeks" name="four_weeks"
      domain="[('date_order','&gt;=',(context_today() +
                relativedelta(weeks=-4, weekday=0)).strftime('%Y-%m-%d'))]"
        />
</xpath>

{'search_default_four_weeks': 1}]

=====

Another idea is to create a new boolean field on Sales Orders, and run a scheduled job every day to set this ON when an order is 4 weeks old.  Then you can create a Record Rule to limit access to older orders.

This is an example of the Python code, but you'd need to create a new module to run it (Scheduled Actions can't run Server Actions):

for rec in records:
  rec['x_recent_order'] = False
  if rec.date_order > (datetime.datetime.today() - datetime.timedelta(weeks=4)):
    rec['x_recent_order'] = True 

x_recent_order is the new boolean field.  Hope this helps!

Refer Odoo developer documentation https://www.odoo.com/documentation/13.0/reference/security.html

a domain used to check whether a given record matches the rule (and is accessible) or does not (and is not accessible). The domain is evaluated with two variables in context: user is the current user’s record and time is the time module

You can use only two predefined variables in the record rule. 

user

    It's the browsable object of res.users model. 

time

    is the time module which provides various time-related functions