Create a file "/etc/profile.d/php.sh". Use pathmunge to add the path to your php bin you want as default on line one and save the file.
Reload your profile afterwards by logging in again.
Now if you do a which php and php -v you should see the following output in my case
[root@host etc]# which php
[root@host etc]# php -v
PHP 7.3.4 (cli) (built: Apr 2 2019 13:48:50) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.3.4, Copyright (c) 1998-2018 Zend Technologies
with the ionCube PHP Loader (enabled) + Intrusion Protection from ioncube24.com (unconfigured) v10.3.4, Copyright (c) 2002-2019, by ionCube Ltd.
This is the preferred way to accomplish this task using tools that are already supplied on a minimal install. This also allows scripts and commands to hit the correct php binaries when accomplishing other tasks. Commands like, pear, pecl, phar, php-config. You want your experience to be global when setting the default, otherwise you might wind up still getting version 5.6's tools when trying to install an extension or complete another task.