While looking online for some fun pieces to play I came upon this section of music from This will be the day [RWBY] (https://musescore.com/user/3321186/scores/1094386). In this music there is a common occurrence of a "double octave" chord with one hand (for ex. F-A-F[8va]-A[8va]; See Image). I haven't found a way to play this as my hand doesn't seem large enough, so I've been just cheating by alternating between the two octaves. It sounds kind of weird when I do this. So is there any alternative to this or a method that makes playing this possible?
This is not original music but a piano version done by an amateur. Presumably an amateur who is able to play this himself, due to having large hands and/or working on an electronic keyboard with keys narrower than a grand piano.
This is an fff passage which makes this somewhat more annoying. My first choice for a reduced rendering would be to leave off the lower A and the whole second-lowest note in the right hand. That does not reduce not the span of 10 notes overall but it does not employ your index finger at a position at odds with the rest of the fingers (the thumb on its own can usually move quite a bit further from the others).
Harmonically, that's likely the closest you can get to the original. Next choice would be to only play the lowest and the highest note. If your hand is not up for that, leaving off only the highest note is also a possibility but since it engages your index finger again, it's not likely to work better and it disturbs the overall character.
My final choice (and possibly better than leaving off the highest note) would be to only play the highest two notes. That preserves the overall range (and the left hand does provide the bass material after all) and even though it costs substance compared to playing only the lowest two notes, it preserves the brillance.
Of course, yet another option is to check the original from which this has been reduced and then make a decision what would be closest to the character of that. Particularly on an upright piano, chords tend to turn out muddier in character than with orchestral registration, so there may be some sense in thinning out the lower octaves in heavily populated chords.
This looks like sheet music made from a MIDI arrangement, where someone put the melody in, then doubled it in 3rd, then thought "Hey, why not put the whole thing up the octave for the loud part" without thinking of playability at all.
The previous suggestion of just playing the top two notes is a reasonable one. I'd also try playing just the upper note (A-Bb-A-G-A) but in octaves, since you should be able to get that up to a good speed without having superhuman hand size or dexterity.
The LH part is also going to get difficult if you go beyond a moderate tempo— and more importantly it will always be awkward which is different from a piece that is difficult but rewarding to play once mastered. If you're at all comfortable making things up, I'd say play around with different patterns in the LH until you find one that sounds good and is fun to play.
I'm surprised the actual answers haven't yet mentioned the pianistically obvious choice (it was mentioned in a comment) of dropping the lowest note from the right hand. Then the melody will be played in octaves, which makes it stronger, and the harmonizing second voice is still there. This will sound quite the same as the written version. And it should be very playable for anyone who would seriously consider playing this.
The left hand, while not exactly comfortable, is playable as written (even at the notated 170bpm) at least with the following fingering: 5-2-1, 5-2-1, 5-2, 5-2-1 | 5-2-1 ...
I also checked the original, and to me these choices sound ok.