Way to specify Lambda runtime version at the time of deployment

While deploying a python code as lambda function, the runtime automatically assigned to the function is "python 3.6"
The issue with this is - all of my layer code directory structure is built in this manner
< python/lib/python3.7/site-packages/{layer code} >

With runtime = python 3.6, lambda functions errors out with
"Import error: Unable to import module _"

Is there a way, I can specify lambda runtime in config.json file ? or if that's not possible then a workaround to attach a specific runtime version at the time of deployment ?

Awaiting inputs. Thanks!

Start by reviewing the deployment configuration around config.json and the Lambda deployment entry point, then trace how the Python runtime is selected. Compare that behavior with the reported python/lib/python3.7/site-packages layer layout and determine what configuration or documented workaround is needed; done means a deployment can use the intended runtime or clearly documents the supported alternative.

Written by the indexing model from the issue text.