from odoo import api, fields, models


class SaleOrder(models.Model):
    _inherit = 'sale.order.line'

    size = fields.Char(string="Product Size")
    box_size = fields.Float(string="Box Quantity")
    box_calculate = fields.Float(string="Total sq. ft./Box")
    square_feet = fields.Float(string="Sq. Feet/Tiles")
    categ_id = fields.Many2one('product.category', 'Product Category')

    @api.onchange('product_id')
    def onchange_product_id(self):
        for row in self:
            row.size = row.product_id.size

    @api.onchange('product_id')
    def onchange_product_id(self):
        for row in self:
            if row.product_id:
                row.categ_id = row.product_id.categ_id

    @api.onchange('product_id')
    def onchange_product_id(self):
        for row in self:
            row.square_feet = row.product_id.square_feet

    @api.onchange('product_id')
    def onchange_product_id_box_size(self):
        for row in self:
            row.box_size = row.product_id.box_size

    @api.onchange('product_id')
    def onchange_product_id_box_calculate(self):
        for row in self:
            if row.product_id:
                row.box_calculate = row.product_id.box_calculate

    @api.onchange('product_id')
    def onchange_product_size(self):
        for row in self:
            if row.product_id:
                row.size = row.product_id.size

Here this code how can I onchange product_id with categ_id. That means When I select a product the category will show automatically. Please help me