可以如下设置，

 await blobClient.UploadAsync(stream, true, default);
 await blobClient.SetHttpHeadersAsync(new BlobHttpHeaders
 {
    ContentType = contentType
 });

如评论中所述，使用单一方法执行相同操作的有效方法如下，

As mentioned in the comment, the efficient way to do the same with a single method as follows,

await blobClient.UploadAsync(ms, new BlobHttpHeaders{ ContentType = "text/plain"});