You need the LATEST versions Entity Model Features (+v2.0.2), Entity Texture Features (+v6.0.1) to use this pack. This are client-side mods that are available for both Forge and Fabric

OPTIFINE DOESN'T SUPPORT PLAYER CUSTOM MODELS ...yet, just in case.

A part from the Fresh Moves resource pack... but just the expressions

If you are doing emf player animations resourcepacks feel free to use this eye animations in yours, you just have to acknowledge that these expressions were originally part of the Fresh Animations eyes animations from pillagers and endermen. Follow the guidelines of the Fresh Animtions licence. I intend these eyes UVs to be uniform in most player animations so they are compatible with each other.

Any info and fixes are in the Just Expressions wiki

Why am I still doing this?... I should be doing other stuff, this is not even my hard work... just playing with things I cannot comprehend but still... just to feel better with myself?... Are you still watching? well... to apply this eyes follow the guide bellow:

To animate the eyes go to the Just Expressions wiki. All supported eyes are there. Here are some examples of things you must get in the end.

Finally some real examples. The final example also shows the 2x3px eye combination with the third eyebrow offset

Credits:

FreshLX: Creator of Fresh Animations. The pillager and endermen animations of the Fresh Animations texture pack were used as the base of this resource pack.
Traben: Creator of ETF and ETM mods and of the custom player models feature. Optifine doesn't have this.
BoZo-Xo2 & CoolRanchChris: Creators of the original Fresh Player Animations resourcepack (The pack where Fresh Moves and Just Expressions are made from) and members of the Traben's discord server.

Fresh Player Animations and other player animation packs can be found in the Traben's Discord Server in the etf-emf-pack-list channel. Be sure to take a look.