It actually exists specifically for SRT or other text-based subtitles
https://support.plex.tv/articles/subtitle-offsets/
There’s a number of related feature suggestions discussion an option
- use different level increments → Fix subtitle offsets
- automatic lip-sync for subtitles → Feature Request - Lip Synch / Audio Offset
- use a keyboard shortcut to increase/decrease the offset → Keyboard Shortcuts for Subtitles Offset
- increase max offset → Increase maximum time offset for Subtitles
Please comment/vote in the suggestion threads applicable to your use case in order to help us avoid distracting or cannibalizing votes. Unless I’m missing some unique aspect of your suggestion I’ll close this thread as a duplicate.