Panasonic GH5S has a Micro Four Thirds lens mount and currently there are 121 native lenses available for this mount.
The latest released lenses that are compatible with the GH5S are the Rokinon 7.5mm f3.5 Fisheye, the Samyang 7.5mm F3.5 Fisheye MFT and the OM System 90mm F3.5 Macro.
Panasonic GH5S doesn't have a sensor based image stabilization system but 34 of these lenses already comes with optical image stabilization.
Since Panasonic GH5S has a Four Thirds sensor, it has a focal length multiplier of 2x so you have to multiply lenses original focal length with this multiplier to find the Full Frame equivalent focal length of the lens when mounted on GH5S.
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Panasonic GH5S Lenses with Image Stabilization
Panasonic GH5S Lenses with Weather Sealings