When you see an antenna designed for a specific band you can adjust it to any other band by scaling it, no matter the antenna! With the exception of Slot fed Microwave and nm antennas.
Trying to build a slot fed 80m would not only be stupid and time consuming, it would be quite probably the most useless antenna you could ever build.
When you pass your foundation, the first thing after you have a transceiver you should do is this Build a 20m dipole.. its so easy 20 / 2 =10 10/2 = 5 thats 5m a leg for both sides of the dipole, plus or minus a little trimming. you don’t have to buy a centre you can use a offcut of waste pipe, you don’t need expensive insulators either the same wastepipe will work! and to feed it solder the braid of your coax to one side and the other to the centre live feed. Waterproof it (CowGum is great) and then finally make an ugly balun 6 or 8 turns of coax in a loop taped and Vola.
Don’t buy if you can build its a lot cheaper