With the division of Ireland after the war of Independence, Northern Ireland had, until 1972, it’s own parliament, with statute-making powers. The freely-available volumes listed below cover the first decade; additionally, I have found a single volume of statutory instruments.
A selection of laws from the whole period are available from Legislation.gov.uk. Bailii has the second edition of The Northern Ireland Statutes Revised, which includes nineteenth century legislation.
With thanks to JC, for finding these volumes.
STATUTES
1921: 12 Geo 5: https://books.google.co.uk/books?id=d6cvAQAAMAAJ
1922: 12 & 13 Geo 5: https://books.google.co.uk/books?id=i6cvAQAAMAAJ
1923: 13 & 14 Geo 5: https://books.google.co.uk/books?id=xacvAQAAMAAJ
1924: 14 & 15 Geo 5: https://books.google.co.uk/books?id=hPBLAQAAIAAJ
1925: 15 Geo 5 / 15 & 16 Geo 5: https://books.google.co.uk/books?id=ofBLAQAAIAAJ
1926: 16 & 17 Geo 5: https://books.google.co.uk/books?id=wPBLAQAAIAAJ
1927: 17 & 18 Geo 5: https://books.google.co.uk/books?id=9vBLAQAAIAAJ
1928: 18 & 19 Geo 5: https://books.google.co.uk/books?id=3NpLAQAAIAAJ
1929-30: 19 Geo 5 / 20 Geo 5: https://books.google.co.uk/books?id=39pLAQAAIAAJ
1930: 20 & 21 Geo 5: https://books.google.co.uk/books?id=4dpLAQAAIAAJ
1931-2: 21 & 22 Geo 5: https://books.google.co.uk/books?id=Rv1QAQAAMAAJ