Online FFmpeg documentation is generated nightly and corresponds to current development. You are encouraged to refer to locally installed documentation for older versions of ffmpeg:
ffmpeg -h and
man ffmpeg. Since FFmpeg development is very active, and since repositories generally provide relatively out-of-date ffmpeg, it is likely your ffmpeg build does not support many (or any) filters. Some filters, such as
drawtext, require external libraries and ffmpeg packages provided by most distros are generally not built with support for these filters.
ffmpeg -filters will provide a list of filters supported by your version of ffmpeg. If you are lacking some or all filters it is likely due to using an old version of ffmpeg or possibly due to the way the ffmpeg package was configured.
You can use a recent static build or compile ffmpeg (see ffmpeg compile guide for CentOS) to get a build that does support whatever filter you need.