I know that I could simply use the geometry package but is there a way to invoke that behaviour directly in the classes?
As far as I know, KOMA always tries to keep the bottom margin twice the size of the top margin.
Short answer: No, there is no class-inherent way.
Longer answer: The KOMA-script classes use the typearea
package to create page margins according to "construction by dividing" - see chapter 2 and especially sections 2.1 and 2.2 of the KOMA-script documentation for details. You may vary the divison factor and add a binding correction. Also (quoting from p. 37),
there are cases where the text body has to fit exactly some specified dimensions. At the same time the margins should be well spaced and a binding correction should be possible. The
typearea
package offers the command\areaset
for this purpose.
In other words, even when using \areaset
, the bottom margin will be twice the size of the top margin.