You're amazing, thank you Jess!I’d try to find people who have worked at the firm / who are trainees or recently qualified on LinkedIn and see if they can give you more guidance on what they experienced.
I would also check websites like Glassdoor to see if there are any interview submissions on there (might not be if it is a small firm, but still worth checking).
I’d also look to see if the firm has described its company values on their website (check any “about us” sections on their website). In most cases, interviews will be aligned in some way to the values that the firm has and expects of its people, and so this can be a reasonably good guide to the type of evidence of your skills/qualities/attributes they would like to see in an interview.