Can I customize the contact layout, and does Votel have custom objects like GoHighLevel?

Everything on the contact record is customizable. Under Conversations you can change the contact layout: on the right are custom tabs, inside them custom sections, and inside those custom fields. You can create new tabs and new sections (groups), add custom fields, and rearrange everything. Each section can start open or collapsed and can be one or two columns.

Votel does not have custom objects or relational data between custom entities, so you cannot define new entities with relationships between them, and a contact cannot hold several separate records in a one to many relationship.

What works instead: many people use a custom section like an object. Group the related custom fields in their own section, for example a section that holds the details about a horse, or about anything else you need to track. You can also use different saved views for different types of contacts, and a custom field can use the pipeline column data type to give a contact another stage setting.