MariaDB 10.5

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

CREATE TABLE Table1( colA VARCHAR(10), colB INT)
INSERT INTO Table1 VALUES
('colE', 0),
('colF', 0)
CREATE TABLE Table2( colE INT, colF INT, colG INT)
INSERT INTO Table2 VALUES
(1, 1, 1),
(1, 1, 1)
SELECT GROUP_CONCAT( CONCAT('SUM(',colA,')') SEPARATOR '+' )
  INTO @sql
  FROM ( SELECT t1.colA 
           FROM( SELECT *
                   FROM information_schema.columns
                  WHERE table_name = 'Table2' ) AS c
           JOIN Table1 AS t1
             ON t1.colA = c.column_name ) AS t;

SET @sql = CONCAT('SELECT ',@sql,' AS total FROM Table2'); 
                  
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;  


total


4