Example 1

              from odoo import fields, models

class InheritedModel(models.Model):
    _inherit = "inherited.model"

    new_field = fields.Char(string="New Field")

<record id="inherited_model_view_form" model="ir.ui.view">
    <field name="name">inherited.model.form.inherit.test</field>
    <field name="model">inherited.model</field>
    <field name="inherit_id" ref="inherited.inherited_model_view_form"/>
    <field name="arch" type="xml">
        <!-- find field description and add the field
             new_field after it -->
        <xpath expr="//field[@name='description']" position="after">
          <field name="new_field"/>
        </xpath>
    </field>
</record>

to get inherited.inherited_model_view_form
1. enable developer mode
2. go to view form of parent module
3. go to edit form option
4. inspect external ID option

Example 2

from odoo import models, fields

class SaleOrderInherited(models.Model):
    _inherit = 'sale.order' 

    custom_field = fields.Char(string='Custom Field')

<record id="view_sale_order_custom" model="ir.ui.view"> 
<field name="name">sale.order.custom.form.inherited</field>
     <field name="model">sale.order</field> 
     <field name="inherit_id" ref="sale.view_order_form"/> 
     <field name="arch" type="xml"> 
          <xpath expr="//field[@name='partner_id']" position="after"> 
               <field name="custom_field"/>
          </xpath> 
     </field> 
</record>