Get Current week days from monday to sunday

In general, use SET DATEFIRST 1 to specify that monday is the first day of the week. However, that doesn't solve the issue here. Use this syntax instead:

SELECT DATEADD(week, DATEDIFF(day, 0, getdate())/7, 0) AS StartWeek,
       DATEADD(week, DATEDIFF(day, 0, getdate())/7, 5) AS EndWeek

Demo

SET DATEFIRST (Transact-SQL)

1    Monday
2    Tuesday
3    Wednesday
4    Thursday
5    Friday
6    Saturday
7    (default, U.S. English) Sunday