Hi,
If you need to make changes inside the res.config.settings, lets us explain with an example,
class ResConfigSettings(models.TransientModel):
_inherit = 'res.config.settings'
account_no = fields.Char(string='account',
config_parameter="module_name.account_no")
then we have to inherit and add it to the view,
<record id="res_config_settings_view_form_inherit" model="ir.ui.view">
<field name="name">res.config.settings.view.form.</field>
<field name="model">res.config.settings</field>
<field name="priority" eval="25" />
<field name="inherit_id" ref="account.res_config_settings_view_form" />
<field name="arch" type="xml">
<xpath expr="//div[@data-key='account']/div[2]" position="after">
<h2>Test</h2>
<div class="row mt16 o_settings_container">
<div class="col-12 col-lg-6 o_setting_box" title="">
<div class="o_setting_right_pane">
<label for="account_no" />
<div class="text-muted">
Account No:
</div>
<div class="content-group">
<div class="mt16">
<field name="account_no"/>
</div>
</div>
</div>
</div>
</div>
</xpath>
</field>
</record>
Also you can check this video explaining the same in v12: How To Add Settings/Configuration For Module in Odoo
Thanks