Yes, he has more transformations. From the wiki, Drive Knight has 6 Tactical Transformations. These are:
- Knight (桂馬, Keima): Drive Knight shapes his lower body into that of a horse, giving him the appearance of a centaur.
- Silver (銀, Gin): Drive Knight forms a long sword.
- Chariot (香車, Kyōsha): Drive Knight transforms into a sleek motorbike.
- Flying Chariot (飛車, Hisha): Drive Knight transforms into a bulky compact projectile with four wings and forms rocket engines that propel him forward.
- Bishop (角, Kaku): Drive Knight transforms into a large humanoid robot with a crested helmet.
- Gold (金, Kin): Drive Knight adds a layer of armor to his body. His hair turns white and his armor flares between its plates.
All in all, he has a total of six transformations. The ones you saw were the Knight and Chariot transformations. As @AkiTanaka mentioned, these are named after shogi pieces.