Attempting to Create a model with unknown columns count.

I would like to create a model in ML.net with unknown count of columns.

I load the data from a text file. The first column will always be the result label. After that, it can be 2, 3 or even 20 columns with custom names(Header).

I tried creating a class like this

 public class NewData
     {
         [LoadColumn(0)]
         public float Label { get; set; }
    
         [LoadColumn(1, 100)]
         [VectorType(100)]
         public float[] Features { get; set; }
     }

I wrote 100 because it will never be more than 100 columns.
After that, how could I create the pipeline and the model?
Would I need to concatenate all the columns inside Features?

Thanks