Modify indentation in Project Online via REST API's

Hello community,

Need assistance in updating a Task indentation in Microsoft Project Online(PWA) via REST API's.

My goal is to change the task indentation from OutlinePosition 1 to OutlinePosition 1.1 and vice versa.

Tried something from the article here, where he managed to indent the task while creating it, where as I need to manage the indentation while updating it.

Expected Output Required

Thanks in advance.

Note: I'm trying to achieve this using PowerPlatform