There isn’t really a built-in way. You can use PlayerPrefs but that’s not really made for saving a game save. More for saving things like ‘was the music muted’, etc. If it’s going to be something simple like storing the player’s high score, PlayerPrefs could be sufficient.
A proper saving system is quite involved. The RPG course covers a full saving system. It’s generic, so it can be used for any game. It has some drawbacks because it uses a binary formatter that has since been deemed unsafe by Microsoft. However, @Brian_Trotter has written a whole thing on converting the binary bits to json instead. Still the same system, just saves as json instead of using the (now unsafe) binary formatter. You can find info here: Saving System Upgrade: Replacing BinaryFormatter with Json.NET