IC: Forgotten realms, D&D 5e, open world, small groups.
Unfortunately, it ends up being a bit of a quantity vs quality problem.
Quite a few folks will submit an RTJ where they mention a race and a class and then stop talking.
One thing that I find helpful is to explain a bit about what sort of tale you are going for. Obviously not plot points, per se, since you are going for an open world feel ... but more of a 'hey, this is a little about me and the types of games that I like to run.'
On the other end of the spectrum, some of the RTJs I have had to sift through are retreads from some older, different game and the folks submit a fully realized character (complete with backstory, important NPCs, etc). These can also be a bit problematic, depending on if the player ends up being inflexible on the details of their RTJ.
I mean, I get it, there was once a game that players like this really enjoyed and their RTJ contains a character that was in said tale ... but it is not necessarily also true that this perfect version of this perfect character will be a good fit for a completely different tale hosted by a completely different DM with a completely different gaming style.
Regarding how much of a character's backstory I am interested in seeing during the RTJ ... I use the miniskirt rule. That is, an RTJ should be long enough to cover the important parts, yet also short enough to keep my attention.
YMMV