IRL chairman Tony Grant said the 2030 men's and women's World Cups will expand to 12 and 10 teams, from 10 and eight in 2026.
Eight men's teams will qualify automatically, while four others will earn places through a World Series.
The IRL selected Pacific-USA as host, with the ARLC and NRL hosting and the ARLC organising alongside the IRL.
Grant said the five-week tournament will visit five cities, yet to be selected, across the Pacific and United States.
Men's and women's matches will share each city on the same weekend, with 11 games played weekly.
Each stop is planned as a Magic Round-style event, using stadiums suited to multi-day pool matches.
Grant said the strategy aims to attract broadcasters, government partners and fans while opening new territories.
The Wheelchair World Cup will take place concurrently in France.
The expanded format remains undecided; nations provided feedback at the IRL AGM and Congress in Sydney over the weekend.