There's a part in my story where a group of people begin speaking in unison, and it feels weird for me to just write that dialogue like any other line. I keep thinking it needs to somehow look different to make it clear it's coming from multiple voices instead of just one. I considered using "Zalgo" font... "̵̛̹̩̽̒͂̽̇͂̌̕͝W̷̘̦̞̻̆̃̇͝e̷̛͕̝̯̮͒͋̒͊̕͝ ̴̧̡̡̲̞̲̝͕̭͓̦͇̬͛̃́̈́̿͐̓̿a̴̧͈͇̞͔̭̫̰̖̜̓̉̈̃̿̊ŗ̷̩̯̃̽́͘ė̶̺̥̪̤̤̭̗̩̥̩͜ ̴̧͖͔̱̟̝̩̱̼̝̭̼̰̜́̂̿͛͒̿̀̿́̌̂̕͠ͅL̷̨̠̝̺̱̩͚̙̮̘̭̦̺̰̅͆̾͐ȩ̶̜̯̝̪͖̇͌͌̑̃̔ͅg̶̡̪͈̖͕̋͗̈͛͒͑̍̒̐͗͘͝͝i̶̱̲̮̙̱̮͕̤͂͜ơ̸̧̧̤͓̘̟̣̼̲͈̻̩̋̈́͋̅̆̈́̇͆͝͝͝ñ̵̛̬̯͈͕̮̭͔͉̫̰̘̖̿͊́̆͜.̸̨̛͙͍̝͓̭̙̗̰̣̼̾̐̄̀̔̀́̌̃̾͠ͅͅ"̴̥͌̀̐̊̈́̀̈́͛͘̕͘͝͝͠ͅ ...but that doesn't really show up all that well on Word. Any suggestions?
Why don't you use a screen shot? Type it out in the program that it does appear right in, screen shot it and then paste it into word as a picture.
Writing is linear. What you are trying to capture is a visual art, but that is less adept for revealing a changing story. An animation may be better suited to what you want. Font tricks like you are suggesting aren't writing. Writing models perception which DOES linearize perception in the same way your brain processes complexity. Even if you are multiprocessing, you are focusing on one element at a time, and may miss focusing on concurrent events. So shift your writing focus to the fragments the character IS processing.
This is going to be a book aimed at elementary to middle school aged kids, so there's a little wiggle room when it comes to adding visual elements to the writing.