Row height and Column width can be changed with the RowHeight and ColumnWidth properties.

Macro to change the row height of Row 1 and column width of Column A:

Sub HeightWidth()

    Rows("1:1").RowHeight = 30
    Columns("A:A").ColumnWidth = 30

End Sub

Macro to change the row height of Rows 1 to 5 and column width of Columns A to E:

Sub HeightWidth2()

    Rows("1:5").RowHeight = 30
    Columns("A:E").ColumnWidth = 30

End Sub