@tuanphan I've tried the <br> tag but that only adds the line break in the default caption and not in the lightbox caption. Any other ideas?
edit: I've found a janky workaround by using a 3 per em whitespace unicode to organise the text in the caption abit better. It's a little weird but it's the only thing that I've found to affect formatting in the caption.
Unfortunately line break unicodes I've found do not work.
Where I am at, at the moment:
It looks decent in mobile view but you have to fiddle around with the exact number of blank unicodes to insert. Not ideal but it does the job for now.