If you want to query all taxa, you can use spp_taxonconcept() with query_taxon = "" (assuming your token is already set up):
Alternatively, you can retrieve, for example, the first three pages of results returned by the API.
All spp_ functions (i.e. spp_distributions(), spp_eu_legislation(), spp_cites_legislation() and spp_references()) can handle a vector of taxon_id which allows bulk analysis. Below we exemplify this feature for the four functions.