In ArcMap 10.5:
Data management > Fields > Alter Field
Sheri,
If you are creating new fields, you can use Add Field—Help | ArcGIS Desktop, you need to set the Alias Field name as a parameter so that during the creation process the model will take it as an input and generate the field with alias name.
If you are updating your existing fields, you can use Alter Field—Help | ArcGIS Desktop, you need to provide the Updated Alias Name that will be reflected once the model has finished executing.
From a schema creation standpoint, it is a good practice to provide alias field names while creating the field itself, however if the occasion arises for updating or altering the fields name we can use the above workflows.
I hope this helps.
~Shan
Any update on this?