Extra information subtitle

Hi everyone, I wanted to know if it was possible to add (from a file) or from the command line in some way, additional information on the subtitle file.
if they are “normal” subtitles (ass or similar) it is simple to modify them and make them specific file by file.
if instead I have Blu-ray subtitles, so for example PGS format, the player VLC allows me to change their positioning but I have to do it file by file and it has to be changed every time.
I wanted to know if it was possible to insert some additional information directly to the subtitles before merging, or add some file that could force the subtitles in size and position.
Thank you all

Welcome!

The Matroska container format doesn’t provide controls such as the ones you describe. So the answer is… no.

that’s bad luck, I was hoping that maybe adding a command line in the subtitle properties directly from mkvToolnix could do something.
Thank you for the reply, have a good day

Amnesia,

Look for Java app named “BDSup2Sub512.jar”
It lets you permanently change the position of PGS and VobSub files.
The original is unchanged. A copy is made to your specifications, then you mux it into the video.
I usually place mine above the original and make it the default.