Example import library TMS WEB Core application

OS: Debian 10 LXDE 64bit
Lazarus 2.0.12
FPC 3.2.2

Where can I find an example of importing library .so and .dll into a web application and an example of creating a library

I'm not sure how to understand this question.
In the web client running in the browser, it is not possible to use an .so, .dll

I would like to set up a library on the server side that clients in the browser can call

Then it depends on what kind of server side technology you use.
If you add it to the server side, the expected way would be to expose a REST API that gives access to these library .so or .dll functions.

Thanks Bruno.