While primarily a performance-fork for older hardware, some archived versions of offered 32-bit builds. Ishiiruka was infamous for sacrificing accuracy for speed (using async shaders and hacky DX11 renderers). You can find these artifacts on GitHub under user TinoDidriksen or ExtremeDude2 .
While the official Dolphin Emulator website prioritizes 64-bit builds, you can still find legacy downloads in their older release archives.
Modern emulation requires more addressable memory than 32-bit systems can easily handle.