Hi Paceli,

You can follow these steps to achieve the desired functionality:

• Create a new compute field to check if the user has Sales Manager rights:
  

​user_has_group_sale_manager = fields.Boolean(compute='_compute_user_has_group_sale_manager')

​@api.depends_context('uid')
​def _compute_user_has_group_sale_manager(self):
​ ​user_has_group_sale_manager = self.env.user.has_group('sales_team.group_sale_manager')
​ ​for sales in self:
​ ​ ​sales.user_has_group_sale_manager = user_has_group_sale_manager

• Inherit the sale order form view:
  <record id="view_order_form" model="ir.ui.view">
  <field name="name">sale.order.form.view.for.unit.price</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='price_unit']" position="before">

​ ​ ​<field name="user_has_group_sale_manager" invisible="1"/>

​ ​</xpath>

​ ​<xpath expr="//page[@name='order_lines']//field[@name='order_line']//tree//field[@name='price_unit']" position="attributes">

​ ​ ​<attribute name="readonly">not user_has_group_sale_manager</attribute>

​ ​</xpath>

​</field>

​</record>

• Upgrade or install the custom module and check if this achieves the required functionality.