There are quite a few features that would be nice to be consolidated into a refresh API update. Top three:
1. Configure refresh schedule from API
2. Retrieve refresh schedule from API
3. Turn on/off refresh schedule from API
Retrieving the refresh schedule along with the refresh history will allow for schedule optimization in a premium environment.
The description of SQL Server 2017 Reporting Services REST API said it provides basic CRUD operations that can be done on folders, reports, KPIs, data sources, datasets, refresh plans, subscriptions, etc.
However I cannot find the REST API about refresh plans or schedule refresh from the document or sdk.