hr_timesheet_view.xml

<?xml version="1.0" ?>
<!-- Copyright 2020- Le Filament (https://le-filament.com)
     License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl). -->
<odoo>

    <record id="hr_timesheet_line_tree_no_create" model="ir.ui.view">
        <field name="name">account.analytic.line.tree.no.create.inherited</field>
        <field name="model">account.analytic.line</field>
        <field name="inherit_id" ref="hr_timesheet.hr_timesheet_line_tree" />
        <field name="arch" type="xml">
            <xpath expr="//tree" position="attributes">
                <attribute name="editable">top</attribute>
            </xpath>
            <xpath expr="//field[@name='project_id']" position="attributes">
                <attribute
                    name="options"
                >{'no_create': true, 'no_open': true,}</attribute>
            </xpath>
            <xpath expr="//field[@name='task_id']" position="attributes">
                <attribute
                    name="options"
                >{'no_create': true, 'no_open': true,}</attribute>
            </xpath>
        </field>
   </record>

   <record id="hr_timesheet_line_form_no_create" model="ir.ui.view">
        <field name="name">account.analytic.line.form.no.create.inherited</field>
        <field name="model">account.analytic.line</field>
        <field name="inherit_id" ref="hr_timesheet.hr_timesheet_line_form" />
        <field name="arch" type="xml">
            <xpath expr="//field[@name='project_id']" position="attributes">
                <attribute
                    name="options"
                >{'no_create': true, 'no_open': true,}</attribute>
            </xpath>
            <xpath expr="//field[@name='task_id']" position="attributes">
                <attribute
                    name="options"
                >{'no_create': true, 'no_open': true,}</attribute>
            </xpath>
        </field>
   </record>

</odoo>