It would be nice to have an option to automatically enable this checkbox:

to allow reactions and discussions for the newly created release.

This GitHub feature is described here: https://github.blog/changelog/2021-04-06-releases-support-comments-and-reactions-with-discussion-linking/

Here is an example of a release with this feature enabled:
https://github.com/webpack/webpack/releases/tag/v5.37.0

In terms of API, I think it may be the discussion_category_name field in the "Create a release" call: https://docs.github.com/en/rest/reference/repos#create-a-release