CPU instructions are not toggle-able in settings (and they never were), if your CPU has a certain instruction set and RPCS3 supports it, RPCS3 will use the instruction set and there's no way to disable that from the UI.
Desktop: Ryzen 7 5800X, Radeon RX 6800 XT, 2x8G DDR4 3600MHz, Manjaro Linux
Laptop: Ryzen 9 5900HX, Radeon RX 6700M, 2x8G DDR4 3200MHz, Manjaro Linux
Old Desktop: AMD FX-8350, Radeon R9 280X, 2x4G DDR3 1600MHz, Manjaro Linux