Yep. Use the Change Actor Image command - tab 3 of event commands.
This changes someone in your party, not an NPC/event - if you want to do that, you would either use the Change Graphic command within the Set Move Route command for a temporary change, or turn on a switch and add a new page to the event, conditioned by that switch, with a different graphic, for a permanent change.
Your profile doesn't say what version of the engine you're using, and most new members are using MV, but you posted in the Ace support forum. In this case it doesn't matter, because it's the same for all versions. But it might be a good idea for you to update your profile and state what engine you're using so we don't mistakenly give you wrong instructions for future help requests.