_inherit = "product.template"
_description = "Product"

branch_ids = fields.Many2many('res.branch', string='Branch', help="Branch associated with this product template")

@api.onchange('categ_id')
def _onchange_categ_id(self):
    """Sets branch_ids based on the selected category's branch_ids"""
    if self.categ_id:
        self.branch_ids = self.categ_id.branch_ids
    else:
        self.branch_ids = [(5, 0, 0)]  # Clears the branch_ids field

i want to passed the value but dont want auto fetch the data user will select it on their choice based on associted with category in form of dropdown how i will do that