no
AT MINIMUM; you want two float switches (second one is an emergency backup that is placed a little higher than the normal level one so it cuts off the pump in case switch one fails)
both need to be wired in series to a relay that actually powers the pump. Why do you need a relay? Simple - the heat generated by 120v surging through the delicate reeds in the float switch can cause it to permanently fuse together forcing the pump to stay on or never come on depending on how its setup.
float switches have a bad rap due to their high failure rates so its important that as part of your weekly maintenance you verify the float switches work (move them up and down with your fingers and make sure it turns the pump on and off). I would go step further and just replace them every 4-6 months with new ones and soak the old ones in vinegar for a couple days and them swap em back at the next interval. Snails can also hang out on the switch and their weight will keep the float on the switch from floating and activating so make sure you have a snail guard around the switches or better yet - keep snails out of your sump! Putting a baffle in front of the switches will also help stop them going off if you ever get some waves in your sump.