Certain countries have far more arable land than others. There are multiple reasons for this, but geographical location makes a huge difference. There are good reasons that Greenland is generally inhospitable while China has 1.4 billion people.
This map here displays the percentage of arable land by country:
The places with the best farmland seem to be Europe, Caribbean, South Asia, and West Africa. I know India and Bangladesh are very fertile thanks to mountain rivers, but overall placing your island next to a country with lots of arable land will generally lead to your new landmass also having the right climate and other attributes to have lots of cultivated land. An Egypt-sized island can't really fit in Europe, but a large island just south of India Delhi is( 28.7041° N, 77.1025° E ) or west of Nigeria Lagos is ( 6.5244° N, 3.3792° E ) would be good locations for your island.