SQL Server 2019

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create table Table1(col int);
create table Table2(col int);
create table Table3(col int);
insert into Table1 values (4),(5);
insert into Table2 values (4),(5);
insert into Table3 values (4),(5);
6 rows affected

select * from Table1;
select * from Table2;
select * from Table3;

col

4

5

col

4

5

col

4

5

declare @sql nvarchar(max);
with t as (
	select n from(values('Table1'),('Table2'),('Table3'))t(n)
)
select @sql = String_Agg(Concat('Update ', QuoteName(n), ' set col = 5 where col = 4; '),'')
from t;

exec(@sql);
3 rows affected

select * from Table1;
select * from Table2;
select * from Table3;

col

5

5

col

5

5

col

5

5