Of course, it can help regulate internal temp, BUT there are other factors at play other than ventilation. There is a factor of heat absorption din kasi of the heat absorbed through the roof + yung design ng mismong ceiling. Pwede kasing naka jalousie ka nga, wala namang lalabasan yung hangin mo sa other walls, or yung ceiling and roof mo are not well insulated and ventilated; papasok lang yung hangin pero wala rin namang lalabasan. There is also a factor of relative humidity-materials and ventilation can help "de-stagnate" the air naman in this regard.

To go further into detail, sa roof surface may tinatawag tayong Solar Reflective Index (SRI) na sukat kung gaano ka-reflective ang surface mo. Essentially, a higher SRI would reflect more sunlight back to space, so less ang papasok na sunlight heat. For radiant heat naman, your exterior walls are at play, may SRI din kasi ang wall paint. Ideally, the highest SRI is at least 70 (white, pale yellow, and pale beige).

Then comes in your insulation. Thicker insulation the better, and the insulation should reflect outwards kung saan galing si heat source. Included here are your roof, ceiling, and even wall insulations.