Use pitch shifter pugin and master pitch to achieve time stetch effect,like:Time stretch hack for FMOD - YouTube
I set 3 lable of speeds, 1x, 2x, 3x
When accelerating, the sound quality of the sound will deteriorate when the playback is accelerated in Unity, and the diffusion of the sound image will diverge, like a spread effect .but this is not a must every time. FMOD Time Stretch in unity - YouTube