Does anyone have a good visual representation of the 3 different types of plate? I appreciate any and all help!

Two books I'd recommend for that are Charles Ffoulkes' Armour & Weapons and Christopher Gravett's Knight . The first is a sort of primer on medieval armour and the evolution of chain to plate, lots of illustrations and a few b&w photos. The second is one of the "big" Osprey books focusing on the evolution of the armoured English knight from Norman chevaliers to Elizabethan knights, a bit more pricey but has several color plates (one for each "stage") that illustrate the differences I think you are looking for.

PS- Not sure of the forum etiquette for posting ISBNs so I didn't. Still both books are fairly recent and you should be able to order them from any mass market bookstore.

Since the Anime Berserk is the closest representation to the Anima RPG (that covers similarities on more parts of the game system./world than any other anime IME) I would defer to that as a cosmetic example of what these armor types look like. You can see standard issue basic full plate in many of the chapters where the Hawks are laying siege to castles. Full heavy plate can be see on distinguished fighters throughout the series, and full field plate is featured on the Generals of armies.

In the manga, the main characters (Guts and Griffith) both come into possession of more complete suits of plate armor, the final ones being good examples of the complete coverage described in the Anima description for Full Field Plate. see: Gut's Full Field Plate