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As mentioned in the comments, this is entirely dependent on the client, and not all clients handle redirects in the same way. You can find a decent explanation of the redirect codes and why a 301 should drop POST data on Stack Overflow.
When working with a 301 (and often a 302) redirect, most browsers will discard POST data and make a GET request. This is mostly because browsers have always done this, and POST requests most commonly come from web forms, so it makes sense that the redirect results in a GET, allowing for the browser to display a different page without interfering. This is not the case for things like PUT or PATCH requests, as they cannot currently be sent by web forms and typically play by different rules.
If you are looking to maintain the POST data on a 302 redirect, you should consider using a 307 redirect instead. A 307 request should maintain the request method, and the request body as a result.
If you are looking to maintain the POST data in a 301 redirect, there is currently a draft for a 308 status code that would work like the 307, but be permanent.
You can force the redirect to use a GET request with a 303 redirect. It works very much like a 302, but it enforces that the request method is always a GET request. It’s often used in APIs for asynchronous tasks.