If you want to edit the path that the environment for your Spyder is installed. The command of conda create --prefix /path/to/new/location/env_name is correct.
You can access this environment by conda activate /path/to/new/location/env_name.
Though when you create a new environment path, by default no packages will be installed on the environment. you will need to install the packages you want on your environment.
Further more there is another method, but this will modify the default path of future environments you create.
If you edit your .condarc file and add or modify the envs_dirs section in the .condarc file the following below to the file:
envs_dirs:
- /path/to/new/envs/location
Note: you can verify the change with the command conda info --envs
Let us know if you have any questions.
This change will setup the envs path to a new location.