Great info on using the Microsoft Graph Rest APi to interact with Office365 apps like planner, tasks, ect.

https://docs.microsoft.com/en-us/graph/api/resources/planner-overview?view=graph-rest-1.0

Get to know the api

https://docs.microsoft.com/en-us/sharepoint/dev/sp-add-ins/get-to-know-the-sharepoint-rest-service?tabs=http

About the search api

https://docs.microsoft.com/en-us/sharepoint/dev/general-development/sharepoint-search-rest-api-overview

URL examples:

https://blog.lsonline.fr/2019/10/04/microsoft-graph-api-or-sharepoint-rest-api/