Splice offers presets for VST/AU plugins like Serum, Massive, Sylenth, and more. See the selection here.
Presets download directly via the Splice app. Make sure you have the latest update to the Splice app. You can check for updates by clicking on Preferences in the Splice app and clicking “Check Updates”
You can see the preset type near the sample tags when you’re browsing Sounds.
For instructions on loading presets into your VST/AU, please refer to:
Loading Synth Presets from Splice