AIX: How to override variables defined in /etc/environment for a particular user?

A fourth file that the operating system uses at login time is the
$HOME/.env file, if your .profile contains the following line:
export ENV=$HOME/.env
The .env file lets you customize your individual working environment variables. The .env file contains the individual user environment variables that override the variables set in the /etc/environment file. You can customize your environment variables as desired by modifying your .env file.