The answer is yes to both all threads will strip in enough force is used.
Fixed sprocket, do it up as tight as you can by either a chain wrench or riding the bike with the lock nut off and standing on the pedals as hard as you can, stop by using the brake and then put the lock nut on.
Axle will be much easier to strip the thread, so use the spanner of the correct length for the nut provided you do not use all your strength to do the nut up you should be fine or you can use a torque wrench set at the correct figure for the size of thread. Doing nuts and bolts up is like a lot of things in life you learn by experience.
The answer is yes to both all threads will strip in enough force is used.
Fixed sprocket, do it up as tight as you can by either a chain wrench or riding the bike with the lock nut off and standing on the pedals as hard as you can, stop by using the brake and then put the lock nut on.
Axle will be much easier to strip the thread, so use the spanner of the correct length for the nut provided you do not use all your strength to do the nut up you should be fine or you can use a torque wrench set at the correct figure for the size of thread. Doing nuts and bolts up is like a lot of things in life you learn by experience.