The part 77 obstacle clearance surfaces do not support a turn below 400 feet.
There are specifically designed turning departures and the obstacle clearance surface analysis reflects this.
In general, for AEO departures, the surveys are for a straight ahead takeoff. Some runways will have a low level turn AEO for terrain - eg YMHB R30, for many years, had a right hand turn over the bay to avoid high terrain to the northwest.
If an OEI departure requires a turn for terrain, this generally will be a per-Type requirement and the terrain analysis and splay development is a problem belonging to the operator/crew. The aerodrome owner is only going to run the minimum survey (costs) required by regulations.
Bank limits will be per AFM data and/or special procedures negotiated with the Regulator and based on engineering analysis.