Return the last 3 records from an index

I am creating a chat, all I want to do is retrieve the last X records from an index. I do not want to query, I just want the last X records. It is requiring me to use a vector in the query params, I tried making an array of 1536 elements of 0, 0.1, 1 etc, but it sometimes filters the results and does not return the last X records. What is the best way to do this? Please help, thanks!