With ORDER BY:

SELECT k
FROM t1
ORDER BY k COLLATE latin1_german2_ci;

With AS:

SELECT k COLLATE latin1_german2_ci AS k1
FROM t1
ORDER BY k1;

With GROUP BY:

SELECT k
FROM t1
GROUP BY k COLLATE latin1_german2_ci;

With aggregate functions:

SELECT MAX(k COLLATE latin1_german2_ci)
FROM t1;

With DISTINCT:

SELECT DISTINCT k COLLATE latin1_german2_ci
FROM t1;

With WHERE:

SELECT *
FROM t1
WHERE _latin1 'Müller' COLLATE latin1_german2_ci = k;

SELECT *
FROM t1
WHERE k LIKE _latin1 'Müller' COLLATE latin1_german2_ci;

With HAVING:

SELECT k
FROM t1
GROUP BY k
HAVING k = _latin1 'Müller' COLLATE latin1_german2_ci;