then my understanding is to for dbt on top to handle this , please confirm me if it is wrong approach

ya sorry for overlooking, it is clearly said same in documentation as below

If this feature does not meet your normalization needs, we always put the full json blob in destination as well, so that you can parse that object however best meets your use case. We will be adding more advanced normalization functionality shortly. Airbyte is focused on the EL of ELT. If you need a really featureful tool for the transformations then, we suggest trying out dbt.