Artemislib
ArtemisLib 1.13.2, 1.12.2 is a library mod made by the Artemis Games Studio team that allows modders to change the hitbox of entities without the use of coremodding. There are two Entity Attributes added: ENTITY_HEIGHT and ENTITY_WIDTH that can be called from the ArtemisLibAttributes class, and used like any other Entity Attributes.
Requires:
How to install:
How To Download & Install Mods with Minecraft Forge
How To Download & Install Fabric Mods
ArtemisLib 1.13.2, 1.12.2 Download Links
For Minecraft 1.12.2
For Minecraft 1.13.2