下面是使用Newtonsoft.Json Nuget包的一种方法。现在在你的例子中PAR1和PAR3已经激活了，但这是可行的：

void Main()
{
    var match = new [] { "PAR1", "PAR3"};

    var json = JsonConvert.DeserializeObject<JsonData[]>(main);
    
    foreach (var b in json.SelectMany(x => x.PartialBatch).Where(x => match.Contains(x.PartialBatchID)))
    {
        b.Status = "Active";
    }
    
    var modifiedJson = JsonConvert.SerializeObject(json);
}

public class JsonData
{
    public string BatchId { get; set; }
    public Batch[] PartialBatch { get; set; }
}

public class Batch
{
    public string PartialBatchID { get; set; }
    public string Status { get; set; }
}

const string main = @"
    [
      {
        'BatchId': 'BAT1',
        'PartialBatch': [
          {
            'PartialBatchID': 'PAR1',
            'Status': 'Active'
          },
          {
        'PartialBatchID': 'PAR2',
            'Status': 'Inactive'

          }
        ]
      },
      {
        'BatchId': 'BAT2',
        'PartialBatch': [
          {
            'PartialBatchID': 'PAR3',
            'Status': 'Active'
          },
          {
        'PartialBatchID': 'PAR4',
            'Status': 'Inactive'

          }
        ]
      }
    ]";