If you want to publish a video with subtitles, but the platform does not support importing caption files, you can create a video with burned-in captions, making the captions permanently visible to all users.
To learn more about Burned in captions and how to create them read here.
After downloading the Burned-in video, log in to your social media account and upload the video to your profile. For example, you can do this for Instagram Stories or Reels, Tik Tok, YouTube shorts etc. to increase the number of your followers.