All of the current plastic kits give injection moulded rear mud flaps, some in the extended deployed position,
some in the folded up position with poor definition on the folded edges.
These flaps are actually made of rubber with etch parts for the hooks and a stiffener to hold the shape of the side flaps.
They can be posed either up or down, just like the real thing.
Trim the kit part UNDER the tubular mount (Tamiya part shown).
The etch plate is to hold the side flaps in position and to hang the flaps from the model.
Depending on the model used, you may have to trim the top of the brass plate with sharp scissors to fit.
The hooks are very delicate so it is best to leave these off until the closing stages of your build.
If modelling the flaps folded up, best advice is to glue the hooks from behind the flaps and use double-sided tape
to fold the flaps in position.