Hi Jason Longboard, Tortoises can flip themselves providing they have the patience.
They are very clever at doing it, although high carapaced tortoises will most likely have trouble, you should have good gripping substrate, rocks around the enclosure which sometimes help.
A tortoise can stay on its back for a fair few hours before dying, but if you see them struggling to flip do help them.
my smallest hermanns Looi can flip himself within seconds, but my big boy Daisy, he takes over 5 minutes to do so and then if he cant do it he goes to sleep. and i help out