Symfony parse error in output.php when creating project in laravel - laravel

Question

Installed laravel 5.6
Have PHP 7.0 installed as well.
When I try
laravel new sample-project
it creates the required files and dependencies but bails with an error below:
PHP Parse error: syntax error, unexpected '?', expecting variable (T_VARIABLE) in /home/johndoe/laravel/sample-project/vendor/symfony/console/Output/Output.php on line 40
Have a feeling this might be due to issues with the symfony file but not sure how to go about getting the right version or making a change in Output.php
Trying any other command such as
php artisan list
results in the same error
Composer relevant section denoting laravel 5.6 / php 7.1.3
"require": {
"php": "^7.1.3",
"fideloper/proxy": "~4.0",
"laravel/framework": "5.6.*",
"laravel/tinker": "~1.0"
},
Any help would be appreciated.
EDIT
Based on the answer I had to create a project with laravel version 5.5 which means I had to use
composer create-project laravel/laravel sample-project "5.5.*"
That worked.

Answer 1

Laravel 5.6 requires PHP > 7.1.3
you will need to make sure your server meets the following
requirements:
PHP >= 7.1.3

Answer 2

I ended up having to edit the $PATH in my .bashrc file, because it was picking up an old version of php.
> whereis php
> echo $PATH
I found the correct version of php here: /opt/php71/bin
So now my .bashrc file looks like this:
export PATH=/opt/php71/bin:$PATH
This fixed the error I was getting in composer, AND now php artisan also works!
:-D
PS. The version of php that you're using in the shell may be different from the version used to serve your site. That can be fixed in cpanel's php selector.