from odoo import api, fields, models, _

class QuotationTemplateCustom(models.Model):
_inherit = "sale.order.template.line"

unit_price = fields.Float(string="Unit Price")

class UnitPriceChange(models.Model):
_inherit = "sale.order.line"
quotation_template_custom_id = fields.Many2one("sale.order.template.line", string="Quotation Template Custom")
price_unit = fields.Float(string="Unit Price")

@api.onchange('quotation_template_custom_id')
def onchange_quotation_template_custom_id(self):
self.price_unit = self.quotation_template_custom_id.unit_price

<?xml version="1.0" encoding="utf-8"?>
<odoo>
<record id="sale_order_template_view_form_inherit_custom" model="ir.ui.view">
<field name="name">sale.order.template.form.inherit.custom</field>
<field name="model">sale.order.template</field>
<field name="inherit_id" ref="sale_management.sale_order_template_view_form"/>
<field name="arch" type="xml">
<xpath expr="//notebook/page/field[@name='sale_order_template_line_ids']/tree/field[@name='name']" position="after">
<field name="unit_price"/>
</xpath>
</field>
</record>
</odoo>

Thanks Niyas but I won't to use a custom addon to resolve this. Just shared my code