I agree with everybody else! You can use HOB overflow boxes, I use the Eshopps one and it has never lost prime after many power outages, but a drilled one is still your best option. You can pay a very experienced person to drill your tank if you aren’t comfortable and trust me, once you add a sump you will use one on EVERY future build as it makes everything easier from stability to maintenance to hiding equipment.
Here’s a little list of equipment you need vs what you may want for a reef tank.
Need: Heater, powerheads or other flow device, lighting.
Want: Sump, protein skimmer, reactors, controller (ie. Neptune apex), auto top off. I may even be missing a piece or two of equipment.