Use a maximum of two lines of text at a time to prevent obscuring the visuals.
A good guide for effective subtitling (often referred to as "CCCCC" in academic or technical shorthand like "Clear, Concise, Consistent, Correct, and Complete") follows standard industry practices for readability and synchronization. Core Technical Standards subtitle ccccc
A subtitle should stay on screen for a minimum of 1 second and a maximum of 7–8 seconds . Content & Formatting Best Practices Best Practices for Online Subtitling - EngageMedia Use a maximum of two lines of text
Keep each line between 37–42 characters . subtitle ccccc