The simplest way to solve this is to add a calendar table to your database, where in that table you'll have a column for the date, and (at least) a column that indicates if that date is a workday or not.
Here's an article by Aaron Bertrand explaining how you can easily build one. His calendar table is very informative in terms of what is stored in it, but for the purpose if this question a simple bit column called IsWorkDay will suffice.
Something as simple as that would do the trick:

Date        IsWorkDay
2023-07-01  0          -- Saturday
2023-07-02  0          -- Sunday
2023-07-03  1
2023-07-04  1
2023-07-05  1
2023-07-06  1
2023-07-07  1
2023-07-08  0
2023-07-09  0
2023-07-10  1

I've created a sample script for generating a years worth of dates for such a table, including the week day name - you can use it if you want or create your own. Note that my script doesn't take into account holydays, only weekends (Saturday and Sunday). You can run it on db<>fiddle and change to your needs.

Once you have your dates table set up, it's a simple LEFT JOIN query:

DECLARE @UserId int = 7

SELECT @UserId As UserId, 
       C.Date, 
       N.TimeIn, 
       N.TimeOut, 
       CASE WHEN N.Date IS NULL AND C.IsWorkDay = 1 THEN 
           'absent'
       ELSE 
           N.Remark
       END As Remark
FROM Calendar As C
LEFT JOIN NGAC_AUTHLOG As N
    ON C.Date = N.Date
    AND N.UserId = @UserId

Note: You'll need to select @UserId and not N.UserId because when the user is absent, there will be no record of them in the NGAC_AUTHLOG table.
That is also why the condition N.UserId = @UserId is in the ON clause and not in the WHERE clause - because if it was in the WHERE clause, that would effectively convert your left join to an inner join.

Update

@siggemannen commented, rightfully, "You probably want to add some selection on non-weekend dates."

There are two ways to do that - you can either choose to select only work days - so adding a WHERE clause to the query (and removing the now-redundant second condition in the CASE expression) -

...CASE WHEN N.Date IS NULL THEN
...
WHERE C.IsWorkDay = 1

Or, you can change the CASE expression to add a remark for days that aren't work dayes:

...CASE WHEN C.IsWorkDay = 0 THEN 
       'Weekend/Holyday'
   WHEN N.Date IS NULL THEN 
       'absent'
   ELSE 
       N.Remark 
   END As Remark