For Change Sets, you get exactly what you "ask" for. In other words, deploying a Change Set with just the object included gets you exactly that. No layouts, no record types, no fields, no object level permissions, no field level permissions, nothing at all. The base object definition includes the API Name, singular and plural labels, object name gender/starts with vowel, name text/auto-number setting, and Organization-Wide Default sharing settings.
If you want more stuff included, you have to be explicit. If you want fields, you have to include them. If you want record types, if you have to include them. If you want Page Layout Assignments, you have to include both Page Layouts and Profiles. If you want Record Type Assignments, you have to include both Record Types and Profiles.
Unlike Packages, Change Sets are not necessarily complete units of deployment. They are selective edits (hence the name "change set", or a set of changes you want to deploy). The system takes care to include only the changes that you explicitly ask for.
For example, you can deploy a Custom Field without deploying a Custom Object; assuming the Custom Object exists in the target org, the Change Set will only create/update the field specified. A full Package would have included both the Custom Object and Custom Field on retrieval, and would require both if building anything other than an Org-Dependent Unlocked Package.