Here,

Please try this code:

If you simply want to add the age field after partner_id in the project.project form view, use:

<odoo>

  <data>

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

      <field name="name">project.project.form.inherit.age</field>

      <field name="model">project.project</field>

      <field name="inherit_id" ref="project.edit_project"/>

      <field name="arch" type="xml">

        <xpath expr="//field[@name='partner_id']" position="after">

          <field name="age"/>

        </xpath>

      </field>

    </record>

  </data>

</odoo>

after update code please Restart the server and update your module

I hope it is use full