How to copy exact 50 lines of code from a file when a timestamp is there

[jack.chan]

@jack.chan

[2020-12-17] (.\n)+[2020-12-16].\n

you can use the regex
(\[2020-12-17\] (.*\n)+?)\[2020-12-16\]

and capture group 1 instead of group 0 (meaning in UiPath you use .Groups(1).Value instead of .Groups(0).Value

Again this regex can be improved, as i did this in a rush but hope it helps