Hi,

This is the action for the product view,

<record id="product_template_action_product" model="ir.actions.act_window">

        <field name="name">Products</field>

        <field name="type">ir.actions.act_window</field>

        <field name="res_model">product.template</field>

        <field name="view_mode">kanban,tree,form</field>

        <field name="view_type">form</field>

        <field name="search_view_id" ref="product_template_search_form_view_stock"/>

        <field name="context">{"search_default_consumable": 1, 'default_type': 'product'}</field>

        <field name="help" type="html">

            <p class="o_view_nocontent_smiling_face">

                Create a new product

            </p>

        </field>

    </record> 

1. Here in view_mode is Kanban is given first and then followed by tree and then form.

2 .You can change this to  <field name="view_mode">tree,form,kanban</field>  to set default     tree view mode when you select the product button.
3. But you need to inherit this view in your custom module and then change it. For this you     can just copy the above code and give the module reference before the action in id.

<record id="stock.product_template_action_product" model="ir.actions.act_window">

.....

 <field name="view_mode">tree,form,kanban</field>
.....

</record> 

And make sure you give the dependency of the stock module in your manifest file.

Hope it helps,

Thanks

Believe that you want to set a default list for the product.template,

You can inherit the action and change the sequence of the view_mode.

<record id="product.product_template_action_all" model="ir.actions.act_window">

       <field name="view_mode">tree,kanban,form</field>

</record>