@Shaunna
https://www.sony.com/electronics/support/res/manuals/4180/41801791M.pdf
Curiously, iIt gives the screw sizes for other models, but not yours. However, there seem to be three Philips or Pozidrive screws holding the plate to the TV, possibly M5 x 16, and then one hexagon-headed screw, size unspecified, to hold the TV to the cylindrical part of the stand.
This is hexagon-headed so it can be torqued exactly; but if you haven’t got a torque wrench, I can’t see why another slotted-head screw wouldn’t do.
Look for your local Screwfix or Toolstation shop. Take the plate and base with you, and they will be able to sell you the exactly correct hex-headed screw, and make a good guess at the size of the screw needed to fix the plate on.
M5 x 12 means a Metric standard screw with a 5mm diameter, and a 12mm length. Too long a screw, and it won’t tighten enough, too short and it won’t grip enough, so it’s worth getting right.
My favourite bedtime reading is a Sony product manual…
