for i in `cat file1`                            # useless use of cat, may fail on spaces in file1's lines, `...` deprecated
  do 
  for j in `cat file2`                          # same as above; plus: opens, reads, closes file2 linecount1 times
    do
    ssh $i 'systemctl is-enabled "${j}" ';      # creates and deletes a remote network login (linecount1 * linecount2) times
    done
  done

mapfile -t j < file2
while read i
  do    ssh ${i}  <<-EOFSSH
        $(for X in ${!j[@]}
            do echo "systemctl is-enabled ${j[X]}"
            done)
        EOFSSH
   done <  file1

mapfile -t j < file2
IFS=$'\n'
while read i
  do    ssh -T ${i}  <<< "${j[*]/#/systemctl is-enabled }"
  done <  file1