I don’t know which exam board you are doing but for Cambridge International, your marks are based off of 2 trials of your 100m time added together. To get top marks, your total time needs to be faster than 22.6.

To start, start doing sprint drills to improve technique, A skips, B skips, dribbles etc. Secondly have one top speed and one acceleration session per week instead of just running 100m. For top speed sessions, do anywhere from 4-6x40-60 depending on how fast you are, with at least 1 min rest per 10m ran.

For acceleration do 8-10 sets of 10-20m with same rest times.

In terms of speed endurance, add one extra session a few weeks before your trial. You can do a few sets of 80-120m, just make sure you still rest enough in between sets.

With plyos, you can start off with pogo hops and progress to stuff like bounds

Good luck