Recently transplanted a small Peach Tree from indoor to outdoor about a week ago. Tree seems like it was doing fine until today, today is the first day the temperature has reached above 85 and it is extremely bright and sunny(Delaware). A few of the very top leaves have learned a much lighter color, has a whiteish tint to it. Should I put a cover it to try and limit sun exposure?
You've confirmed you did not harden off your peach tree before transferring it outdoors; there's nothing to be done about that now it's planted. It doesn't mean its going to die, just that it will likely suffer from any cool temperatures as well as suffering some sunburn. That just means the leaves you've got now might not look very good, or may even drop off - but the plant should acclimatize and put out new growth, provided you keep it well watered.
Not necessarily, E.B. Keep that plant watered and I would get some shade cloth to cover it for a while. Acclimatization or hardening off takes weeks to ensure the plant's leaves epidermis gets thicker. Otherwise, your plant will get sunburn. Your plant has gotten sunburn and is in a bit of shock. Find some shade cloth; it is a black plastic fabric that comes in different weaves to protect by blocking sunlight in various percentages. I would get a 30 % block and lightly cover your plant for a few weeks. I would also give it a balanced fertilizer if you have not already done so.
Your tree has a chance but covering it to reduce the amount of heat and IR from the sun will help an awful lot! How did you plant this tree? Was it in a pot? Or B&B in a pot? Balled and Burlapped and set in a pot. How did you dig the hole, did you do anything to amend the soil? I hope not?
Send a picture, please. Go to your nursery and ask for shade cloth. Use a few upright bamboo stakes to hold the fabric away from the tree or at least reduce the weight of fabric on the tree. Keep it watered, deeply..what kind of soil do you have? You might need to insert pvc plastic pipe with holes drilled into the soil near the root ball to ensure the water is getting to the roots.