How to downgrade libxml2

[Horst B Simon]

Hi,

I checked the MacPorts documentation, but did not understand on downgrading a port. 
I am trying to install pear using the phar download, but my version of php is failing the install.
By searching on internet I found that it is a compatibility with libxml2, the current installed version
is 2.13.2 and the information is that libxml2 2.13 is not compatible and libxml2 2.12 should be working. 
Is it possible that I can download and build libxml2 2.12 from MacPorts and if so how to do it. 
The older version of php is needed for Horde Webmail 5.22, that’s why I cannot use php8.2 or higher.

Thanks and Regards
Horst Simon