Dear Mukul,
SHD0 could be the most simplest option for that, create Transaction Variant and then assign the same in VOV8 for your specific Sale Order Type in Variant option. Rest there are alot options in order to achieve the same. Use In-completion Procedure and assign it to your particular Sale Document. In FORM USEREXIT_FIELD_MODIFICATION at Include MV45AFZZ you can modify the fields and set them as mandatory with the help of your ABAPER. Ways are many to do this, choice is yours as which option is more convenient for you. Thanks and have a good day ahead.