Hi,

By using the custom model you can add the field in invoice.

1- In your custom module, extend the account.move.line model:

from odoo import fields, models

class AccountMoveLine(models.Model):

    _inherit = 'account.move.line'

    rental_dates = fields.Char(string="Date(s)")

2- And extend the invoice line tree view:

<odoo>

    <record id="view_move_form_inherit_dates" model="ir.ui.view">

        <field name="name">account.move.form.inherit.dates</field>

        <field name="model">account.move</field>

        <field name="inherit_id" ref="account.view_move_form"/>

        <field name="arch" type="xml">

            <xpath expr="//field[@name='invoice_line_ids']/tree/field[@name='product_id']" position="after">

                <field name="rental_dates"/>

            </xpath>

        </field>

    </record>

</odoo>

* After installing this, your invoice lines will have a Date(s) column.

* You can make it fields. Date if you want only one date, or fields.Text if you want a range.

You can also do this using the studio module.

Hope it helps