In vanilla, you can only rotate on the Y axis at 22.5 degree intervals (using the scroll wheel [kb/m] or holding down the LT button and selecting direction with the right stick [controller]). Greater precision and/or rotating on other axii will require using the Valheim+ mod or a mod similar to it.

EDIT: For context, in Valheim the X axis runs west-east, the Z axis runs north-south, and the Y axis runs up-down - rotating on the Y axis means spinning parallel to the ground plane.