Try the following code to generate the update statements dynamically. Once you generated them you can either loop through the table and execute each statement using sp_ExecuteSQL procedure or you can simply highlight the column, copy values into a separate query window and execute.
DECLARE @t TABLE (id INT IDENTITY PRIMARY KEY, [Table Name] VARCHAR(30), [Column Names] VARCHAR(MAX))
INSERT INTO @t ([Table Name], [Column Names])
VALUES
('EVENT_TYPE' -- Table Name - varchar(30)
, 'flow_nm, event_type_txt, event_type_status_txt' -- Column Names - varchar(max)
), ('event_tracking_type', 'event_tracking_type_nm, event_tracking_type_desc, active_ind')
SELECT * FROM @t;
;WITH cte AS (SELECT id, [table name] AS table_name, LTRIM(RTRIM(v.value)) AS column_name FROM @t t
CROSS APPLY STRING_SPLIT([t].[Column Names], ',') v
),
cte2 AS (SELECT cte.id, col.TABLE_SCHEMA, col.TABLE_NAME, col.COLUMN_NAME,
col.CHARACTER_MAXIMUM_LENGTH AS [Length] FROM cte INNER JOIN INFORMATION_SCHEMA.columns col ON
cte.table_name = col.TABLE_NAME AND cte.column_name = col.COLUMN_NAME AND col.TABLE_SCHEMA = 'dbo'
AND col.DATA_TYPE LIKE '%char')
--SELECT * FROM cte2
SELECT id, 'UPDATE ' + QUOTENAME(table_name) + ' SET ' + STRING_AGG(CAST(QUOTENAME(column_name) + '=''' AS VARCHAR(MAX)) +
(REPLICATE('Z', [Length])) + '''', ',') WITHIN GROUP (ORDER BY cte2.Length DESC)
AS [Statement]
FROM cte2
GROUP BY id, cte2.TABLE_SCHEMA, cte2.TABLE_NAME