For indention between parent and child records in a tree view, there is the field_parent tag in the view definition:

<record id="list_view" model="ir.ui.view">
    <field name="name">model view</field>
    <field name="model">model</field>
    <field name="type">tree</field>
    <field name="field_parent">child_ids</field>
    <field name="arch" type="xml">
        <tree string="Partner Categories">
            . . .
            <field name="parent_id" invisible="1"/>
            . . .
        </tree>
    </field>
</record>

Do I have to use the fields 'parent_id' and 'child_ids' or can I use any fields, like 'my_parent_id' or 'child_object_ids'??

Is the invisible parent_id in the view mandatory?

Is a domain in the view action mandatory: [('parent_id', '=', False)] ?

EDIT:

Does the indention work with list views (view_type: form, view_mode: tree,form)?

Thanks for your help.