As The Mandalorian pointed out, different species age differently. In the case of “Baby Yoda,” it’s 50 years old less than a decade after Star Wars: Return of the Jedi, but still a toddler by human standards. In Star Wars: Return of the Jedi, Yoda revealed to Luke he was around 900 years old. So basically, if this kid survives The Mandalorian Season 1 and beyond, it can take the franchise far into the future.
Article source: https://www.cinemablend.com/news/2485548/how-the-mandalorian-may-pave-the-way-for-star-wars-episode-x