How would you share your legacy with future descendants?

I've been contemplating this question on the heels of the passing of an older relative.

It dawned on me that most people know little about their grandparents and that deficit is likely much greater when looking back further generations.

Given that most people are afraid of death / non-existence, how valuable is confidently preserving one's legacy over long time horizons? Meaning, how will future descendants learn about your experiences, values, personality, etc.?

Will you have to make your Instagram public before your death and hope that that service remains popular / available? Will you share your email credentials? Will you count on Google indexed pages persisting hundreds of years from now? Will you deputize family members to collect artifacts (images, text, etc.) in a Google Doc and manage access over generations?

Is this generally a problem that others have considered / valued?