installing CI4 via Composer, but getting error, please help!

CodeIgniter 4 requires php version 7.2 or higher with intl extension.

Yes I know.  All my sites appear to be running PHP 7.3.22, but in console, php -v reports it as 7.0.33 and I don't know how to upgrade it.   I did this in php.ini: extension=intl

What now?

this is not related to CI you just need to config your machine with CI requirements.

You need to give us some information regarding your system.
What OS are you using? are you on a server or desktop?

Run the following commands and send us the result.

$ locate bin/php

$ sudo ls -la /etc/php*

$ sudo find / -name php | grep bin

you are having multiple PHPs on your machine, your Apache server is configured to run your website on your PH7.3 but your CLI php is not.
You have to find the right binary file to your PHP7.3 and set it as default php command.