Resource Overallocation/Fixed Work Query

I have 3 tasks in a project each consisting of 20h work, set to be fixed work scheduled over a 5 day duration starting and finishing at the same time. All three tasks are allocated to the same resource, so MS Project allocates 50% of the user’s time to each task by default. The means that the resource is 150% allocated.

Is there any way to automatically resolve this resource over allocation in this case by MS Project reducing the % allocation to 33% and extending the duration of the task.
Any help would be really appreciated