Must all the values in the same column of a relation have the same length?

It is not necessary for a column in a table to hold the same length data. Though it is mandatory that all the cells of the column must have the same type of data, i.e. numbers, strings and double etc. for example in the following table, the salary and employ columns have variable length and same type data:

Employ Salary
Steve $800
Harris $2,000
Jon $11,000