You can download the OneAgent from the environment API. You have three options here:
You can specify the version you need, or simply download the current latest version.
Downloading the new OneAgent where the current OneAgent exists will be the same as updating the version of your current OneAgent.
Currently there is no method to push a Dynatrace Oneagent via the API, there are only Get commands. All updates have to be done via the API or manually on each server by launching the MSI file
Freshly announced, there is now an EAP for a oneagent API. If you'd like to sign up for that EAP, click the following link: https://www.dynatrace.com/news/blog/manage-thousands-of-hosts-with-the-new-oneagent-on-a-host-rest-a...
This might help fulfill your request.