How the statement bigger size atom have more shielding effect thus low ionization energy?

Larger atoms have more electron shells, which increases the distance between the nucleus and the outermost electrons. This greater distance, along with the presence of inner-shell electrons, results in a stronger shielding effect, where inner electrons repel outer electrons and reduce the effective nuclear charge felt by them. Consequently, the outer electrons are held less tightly, leading to lower ionization energy, making it easier to remove an electron from the atom.