In Guildmaster's Guide to Ravnica, after a Boros Legionnaire is level 5 and has renown of at least 5, the player can become a skyknight (p. 43). The text states:
Skyknights mounted on Skyjek rocs patrol the skies above Ravnica — a regular reminder of the Boros and their concern for justice. If you meet the prerequisites, you can become a skyknight, assuming no official objects. You are assigned a Skyjek roc (see chapter 6 for the stat block) to use as a mount when carrying out your guild responsibilities. Using the roc for personal matters is a significant violation of regulations
Does this mean that a player needs to use the Roc as a mount? Or could they use it as an independent creature, so that it can attack and such on its own turn?
I started at a high level as a paladin so I already have a griffon as a mount, so is the Roc mostly just redundant, or can it attack?