Default at /loot_tables/
/loot_tables/
format: see mc wiki.
https://minecraft.fandom.com/wiki/Loot_table#Recurring_JSON_structures_within_loot_tables_and_other_data_pack_files
note: in Forge, name is required for each loot
name
for example:
{ "pools": [ { "name": "main", "__other": "other......" } ] }