Texture pack help change the visuals of blocks in Minecraft, it can be items, mode, building,…
with different resolutions like 16×16, 32×32, 64×64, 128×128 and includes shaders 

Here you can see some texture pack 

• Default 3D Textures Pack for Minecraft

• YamaRin’s Legacy v2.2 for MCPE

• Elytra Models | Minecraft PE Texture Packs

• Vanilla RTX Normals for MCPE

• Salmon Shader [v1.1.5]

• Rewanston Shader: Hypercolor V0.3

• Biroj Textures for MCPE

• Ale Shader V1.0 (Android/iOS) | Minecraft PE Shader

• Defined PBR – An RTX Resource Pack (1.17.10 Support and more!)

• Hyra Shaders v4 Minecraft PE