Extend Default Keycloak Attribute Character Length


I am running into an issue adding an attribute to some of my users in our Keycloak instance, hosted on our docker image. The default setting for my attribute foobar_id is varchar(255), but some of my users need access to many foobar_ids, which would be beyond the 255 character limit. Is there a convenient way to extend the default character limit of a user attribute? I would likely only need it to be around 400 characters or so. Please advise if there is a better way to do this.