Dimension of output in Dense layer Keras
The answer can be found by just printing
sample_model.summary()

giving
Model: &quot;sequential&quot;
_________________________________________________________________
Layer (type)                 Output Shape              Param #   
=================================================================
dense (Dense)                (None, 32)                160       
_________________________________________________________________
dense_1 (Dense)              (None, 16)                528       
=================================================================
Total params: 688
Trainable params: 688
Non-trainable params: 0
_________________________________________________________________

Indeed, the input_shape argument in a layer that is not the first one is ignored in a Sequential model.