There are a few different screws used to mount a tv to a wall mount. You can get hardware kits with multiple sets of screws. Mount-It! TV Mounting Hardware Kit, Universal VESA Wall Mount Screw, Washer, Spacer Pack (M4 M5 M6 M8) for TV and Monitor Mounting https://www.amazon.com/dp/B0773DHZP6/ref=cm_sw_r_cp_api_glt_fabc_9RQREEQZMKY0Z8JBBHKA
I think you can also get these kits at hardware stores
Good luck. Also keep in mind too that when you buy a VESA mount, the mount itself usually comes with all different diameter screws because there are different size standards for VESA mounts generally depending on how big the display is. Also with these screws are usually various sizes of gap fillers and washers.
You could get a kit like this that includes spacers and longer screws that will hopefully allow a larger mount to work.
I believe most VESA screws are M8.
But you can cover most of the common sizes with a VESA screw kit off Amazon.
Honestly if you wanna replace the screw you can prolly but packs with like 10 - 20 different types of screws from Amazon.
Or just look around on Amazon till you find some that look about the same you know more what they originals looked like. Or if they where more pointy I know some monitor stand screws are weird and I’m not sure hose yours in designed
By the way I know these are not “monitor screws” one of my cheaper monitors base was attached with a pointy style screw. Also you can fine them in black if silver is not what your need
This should have a full assortment for what you need, spacers and long screws. https://www.amazon.com/dp/B0773DHZP6/ref=cm_sw_r_apan_glt_fabc_SFRBYQ92DHE4NK9CAW99?_encoding=UTF8&psc=1
M6x20mm per the manual: https://dlcdnets.asus.com/pub/ASUS/LCD%20Monitors/VG27VQ/VG27V_English.pdf
You can buy the screws on their own from a local bolt and fastener specialist or buy a VESA kit from a reputable supplier: https://www.amazon.com.au/Mount-Hardware-Universal-Monitor-Mounting/dp/B0773DHZP6
Make sure you use the right length screws and do not over tighten.
Just to make sure I understand - is the problem literally that you are trying to put a square peg in a round hole?
If so, you could look at a VESA mounting kit from a reputable supplier like this one: https://www.amazon.com/Mount-Hardware-Universal-Monitor-Mounting/dp/B0773DHZP6/ref=mp_s_a_1_12?dchild=1&keywords=VESA+Mounting+Screws&qid=1625911023&sr=8-12
An alternate solution would be to use a VESA compatible (M4x8mm) stand-off screw like this: https://www.amazon.com/Hilitchi-120pcs-Female-Standoff-Assortment/dp/B018C6NSRU/ref=mp_s_a_1_8?dchild=1&keywords=VESA+standoff+Mounting+Screws&qid=1625911207&sr=8-8. Just note that you may be better off trying to source M4 standoffs locally rather than buying from an unknown brand.
Hope this is helpful.