Possible he was buried in Ford Park Cemetery as most churchyards in Plymouth were fairly full at this time. You would have to pay for a search to be conducted and to obtain details of his grave from the Cemetery. I believe The Box have indexed Parish Burial Registers for Plymouth and have a searchable index on pc if your visit them. The other option would be that his body was returned to his place of birth or where other family members were buried. https://www.ford-park-cemetery.org/cemetery-services/grave-searches