Currently we are working on AEM 6.5.2 which is host on the new Cloud but is not configure as Adobe Experience Manager Assets as a Cloud Service (so to upload images we use the Upload Workflow). We have the Scene7 mode (not Hybrid).
We use Image Preset in order to configure the Dynamic Renditions that are created every time we upload an asset.
It is possible to add conditions over the Images Presets created based on the MIME Type of the asset that is being uploaded?
For example if the Asset MIME Type is GIF we do not want to create the Images Presets with MIME Type JPG
On "DAM Update Asset workflow", there is a step that created Dynamic renditions : Dynamic Media Process Image Assets
Either you need make modification on the Handler that created Dynamic Rendition  or you need create a custom workflow Launcher (as it works on conditions), it detects GIF format and based on the condition, it can enable or disable features.