There is a classic longitudinal study called “the nun study” that has followed a group of nuns since the mid 80’s . Some may have had slightly different educational experiences but most of the other variables (age, lifestyle, no spouses or children, etc) are controlled and similar. They have found that higher education and “higher idea density” (concepts, vocabulary, etc even in speech and writing) correlated with greater cognitive sparing.
From what I recall (haven’t followed the literature lately) cognitive games, apps, etc were/are helpful to keep us and our brains active, but there was not compelling data to suggest that they had any sparing effect. But cognitive and physical exercise is important for our aging selves.