Once the pack is in your resourcepacks folder, you still need to switch it on before the flames shrink.
Enabling the pack
1. From the title screen or the pause menu, open Options and then Resource Packs.
2. In the Available list on the left, find NO FIRE 2.0. It has its own custom pixel-art icon, so it is easy to pick out from other packs.
3. Hover over the icon and click the arrow to move it into the Selected list on the right.
4. If you use other packs that change fire textures, drag NO FIRE 2.0 above them. Packs higher in the list override the ones below.
5.
Quick check that it worked
Test it somewhere safe:
1. Stand on a non-flammable block, such as stone or netherrack, with no wood or plants nearby.
2. Use flint and steel on the block in front of you. The fire should look short and low instead of the usual tall flames.
3. Step into the fire for a moment. The big flame overlay that normally covers the bottom of your screen should be gone, so your view stays clear.
If you still see tall flames, go back to the Resource Packs menu. Make sure the pack is in Selected and sits above any other pack that touches fire.