Ugin,

I want to render several projects at once (the rendering options are the
same). Is there such an opportunity in Cinelerra?

The only way that I know to do something like this, but it is not really what you ask about, is to use "Command Line Rendering" as described in the manual in section 7.3.1.  Partly quoted below:

To perform rendering from the command line, first run CINELERRA-GG in graphical mode. Go to File → Batch Render. Create the batches you intend to render in the batch window and close the window. This saves the batches in a file. ... These settings are used the next time command line rendering is used to process the current set of batch jobs without a GUI.

Then on the command line run:

{path_to_cinelerra}/cin -r batchjob1.xml
{path_to_cinelerra}/cin -r batchjob2.xml
{path_to_cinelerra}/cin -r batchjob3.xml
               however many jobs you have...