It is not possible to change the max length for Name. I don't remember if we have any limitation on DisplayName but it should not be limited by 100 characters.
Note that Name is more of an internal field for editors so you might not want it to be that long
Quan Mai's answer is right. You cannot change the max length for Name because the column Name in Catalog Entry table is nvarchar(100)
About DisplayName, I am using Episerver Commerce 11.6 then this field should not be limited by 100 characters, this field in the database is stored by LongString column - nvarchar(max).
We are trying to extend maxlength of properties like Name and Display Name beyond its default value 100.I have tried to override the Name property and increasing the max length value in my custom Product model but no luck.can any one help me fixing this issue.