What you describe is a "profile module".

You can create a module that depends on the module you have to install and with xml file, you can override existing record. for example, you can change the company name by putting this xml record:

<record id="base.main_company" model="res.company">

      <field name="name">My super company</field>

</record>

This will override the name of the company because the XML ID is identical to an existing one and so it will just update it

In your XML file, i suggest you to put

<data noupdate="1">

and like that, it will just create/update your data's when you install your module. So you can change the value in the interface and when you'll make an update of your module, it will not override the value given trough the interface