out_indices is the index of the layer you'd like to get the feature map from
out_features is the name of the layer you'd like to get the feature map from

These parameters can be used interchangeably, but if you use both, make sure they're aligned with each other! If you don't pass any of these parameters, the backbone returns the feature map from the last layer.

A feature map from the first stage of the backbone. The patch partition refers to the model stem.