Question
Is it possible to update curl on Centos or Ubuntu server with Plesk? For example, install the curl 7.71 version on Ubuntu 18.04 or CentOS 7.
Answer
curl package can be updated as any other package using native system tools. Update will be possible only if the OS vendor has the newer version in its repositories. If there are no packages marked for an update, it means that the server already has the latest version provided by the OS vendor.
The latest available curl version in Ubuntu 18.04 is 7.58.0 and in Centos7 it is version 7.29.0.
It is possible to update curl from 3rd-party repositories, but it is not recommended because curl update can break secure connections to sites, Plesk, and operating system's package managers yum or apt.
Warning: Manual update of curl is not supported by Plesk should be performed on your side at your own risk.
If it is needed to have a newer curl version it is possible to migrate to a newer OS version, shipping the newer curl version.
The list of supported curl versions can be found here: https://curl.haxx.se/download.html.