Yes, there’s an unofficial “remind me” bot you can use at @remindme@mstdn.social ⧉
It can remind you minutes, hours, days, weeks, months or years later. To use it, just mention the bot in a post or reply and include the period you want to be reminded after, for example:
@remindme@mstdn.social 1 week
Reminders can be sent privately if you prefer. To be reminded privately include the word DM, for example:
@remindme@mstdn.social dm 1 week
It should work with any Fediverse platform that supports microblogging, such as Mastodon, Friendica, GoToSocial etc.