Create a Mob using Blockbench and the Minecraft Entity Wizard
Launch the application (or use the web version) and go to File > Open Model . blockbench entity download
If you want to modify existing Minecraft mobs rather than downloading custom ones, the plugin is the most efficient method: Create a Mob using Blockbench and the Minecraft
Once you have found a model, follow these steps to bring it into the software: blockbench entity download
While primarily for skins and maps, many creators share Blockbench projects for Java entities and Bedrock mobs here.
Ensure the model matches your project type (e.g., Bedrock Entity vs. Java Modded Entity) to avoid animation errors. Using the Minecraft Entity Wizard