Crossing a page boundary with a relative branch will incur an extra cycle, but it doesn't make any difference whether the page-crossing branch is a forward branch or a backwards branch.
You can try this out in Visual6502. Enter the program A9 00 F0 EC
(LDA #00
/ BEQ $FFF0
) at address 0000, single-step through the code and see where it ends up after the BEQ
. If you only trust real hardware you could easily verify this on something like a Nintendo Entertainment System.
Obviously to be able to reach page FF with a relative branch you'd have to be executing out of zeropage RAM, and you probably don't want to waste ZP RAM on code since it needs to fit your most frequently accessed data. So that would make this particular scenario unlikely.