In a conventional design (dihedral and/or sweep back for roll stability) in a steady turn (constant rate of roll, pitch and yaw), there is a requirement to hold some into turn aeileron to maintain the AOB. This causes a (slight) adverse yaw, requiring into turn rudder to remain balanced.
In a balanced turn, the rolling tendency is into-turn, not out-of-turn. Hence out-of-turn aileron would be required. The need for rudder in a steady balanced turn comes from the desire to eliminate the sideslip (which you have correctly identified as contributing to the into-turn yaw).
If the turn is not properly balanced and the sideslip is allowed to persist, the slip-roll coupling (dihedral, sweepback or fuselage position effects) will indeed cause an out-of-turn roll. But in most conventional aircraft it won't exceed the into-turn rolling tendency, otherwise the spiral mode would be stable.