I believe you'll need to actually go to your nearest Thai embassy. You'll need COE, covid insurance and will have to book ASQ and other hoops to jump through. You're not getting a visa online.
Are you sure its a visa and not an extension? If it's an extension and he hasn't left the country since it's issue then there is no need for a reentry permit because he has 1 entry i.e. single entry. Any other time after this trip he will need a reentry permit