Datapack help

I want to create a Data pack myself from inspiration of "shiny trims" I got an idea to create it myself because i do not have the money to buy the original Data pack. The Datapack: https://www.planetminecraft.com/data-pack/shiny-trims-make-it-glow/ The Data pack is about when you right click an armor piece it with a glow ink sac it makes so the trim on the armor has a texture that glows in the dark. I checked the post and the creator said it does not use Optifine or any Mods.I checked the glowing trims Resourcepack that a moderator from this server recommended to see for reference and it did not help at all.It is a resourcepack and it work so when you rename a armor it gets the glow, but I want when I right click an armor piece with a item in this case glow ink sac it gets a new texture(the glowing one).Also the paid Data pack uses a Resourcepack which uses color pallets and fsh files.