You can add your terms and condition in Accounting ‣ Configuration ‣ Settings and activate Default Terms & Conditions.
In that box you can add your default terms & conditions. They will then appear on every quotation, SO and invoice.
See this Odoo Documentation: https://www.odoo.com/documentation/user/13.0/sales/send_quotations/terms_and_conditions.html
As your terms and conditions are too big, you can create a new template for the terms and condition and you can call it along the sale_order report, so that there is no need to edit the quotation template and you will get both while printing the report, see this,