CREATE FUNCTION [dbo].[fn_MyFunction] 
 (@ID INT)	
RETURNS @return_table TABLE 
 (Col1 int NULL,
  Col2 int NULL) 
AS 
  --- processing goes here...
   INSERT @return_table
   SELECT @col1_newvalue,@col2_newvalue
RETURN

CREATE procedure MyProc
AS
    
  SELECT col1, col2 from dbo.fn_MyFunction(1)
  
  -- want to store return values for further processing by assigning them to local variables

  declare @newvalue1 int
  declare @newvalue2 int

  set @newvalue1 = col1  
  set @newvalue2 = col2 

  --- start processing @newvalue1 and @newvalue2 further

select col1, col2 
into #temp 
from dbo.fn_MyFunction(1)

select * from #temp

declare @var1 int, @var2 int;

select @var1 = col1, @var2 = col2
from dbo.MyFunction(input);

USE ProofOfConcept;
GO
CREATE FUNCTION dbo.MyFunction (@Input INT)
RETURNS TABLE
AS
RETURN (SELECT @Input AS C1, @Input+1 AS C2);
GO
DECLARE @Var1 INT, @Var2 INT;

SELECT @Var1 = C1, @Var2 = C2
FROM dbo.MyFunction(1);

SELECT @Var1, @Var2;
GO
DROP FUNCTION dbo.MyFunction;

USE ProofOfConcept;
GO
CREATE FUNCTION dbo.MyFunction (@Input INT)
RETURNS @T TABLE (C1 INT, C2 INT)
AS
BEGIN
INSERT INTO @T (C1, C2)
VALUES (@Input, @Input+1);
RETURN;
END;
GO
DECLARE @Var1 INT, @Var2 INT;

SELECT @Var1 = C1, @Var2 = C2
FROM dbo.MyFunction(1);

SELECT @Var1, @Var2;
GO
DROP FUNCTION dbo.MyFunction;

create FUNCTION [dbo].[fn_MyFunction] 
 (@ID INT)	
RETURNS @return_table TABLE 
 (Col1 int NULL,
  Col2 int NULL) 
AS begin
  --- processing goes here...
   INSERT @return_table
   SELECT 1, 2 union all
   select 55, 73
RETURN

end

go

declare @var1 int, @var2 int;

select @var1 = col1, @var2 = col2
from dbo.fn_MyFunction(1)

select @var1, @var2