POST request with httr2 package

It's related to another post

Rather than rvest, I am trying to use the httr2 package to request the data from this link: https://gnomad.broadinstitute.org/api/. I am not that used to it unfortunately, can someone help?

This is what I have tried so far without luck.

library(tidyverse)
library(httr2)

request("https://gnomad.broadinstitute.org/api/") %>%
  req_body_form(
    'chrom' = '1',
    'datasetId' = 'gnomad_r3', 
    'referenceGenome' = 'GRCh38',
    'start' = 55516868, 
    'stop' = 55516908
  ) %>%  
  req_perform()

Error in `resp_abort()`:
! HTTP 400 Bad Request.
Run `rlang::last_error()` to see where the error occurred.