They all spawn naturally

Tameable bosses only spawn in the wild when a hoarder chest is generated (big loot chest that kosts the 6 normal essence types and a max 5 can be on the map) they don't respawn until another hoarder chest is generated

Gigas are limited per map, that a vanilla mechanic, for most maps this limit is 1 to 3

Paragon dinos, the worst way to get paragon souls have a 1 to 2500 spawn chance when a Dino spawns

Also a wolf with 3 paragons is way stronger than a giga with 0
And you are likely to get multiple dozens of wolf paragons before you get your first giga paragon soul

Yes its true. I have 10 paragons godlike dodo and better damage 0 paragon omega giga. But i want 10 paragons godlike giga

Than have fun searching for gigas (any variant ones) and killing them on foot, for the highest chance for quests and paragon