No, different versions of Minecraft have different coding and/or item IDs being used within them. A texture pack for Minecraft 1.16.5 will not work for 1.8.9 or other lower versions since they have a CIT(Custom Item Texture) coding difference. Some people claim that it might work however, be warned that doing so might break your game. So, it would be safe and evident to only use texture packs of the same version.
However, do know that sometimes it does work if they have the same main version. For example, a texture pack or resource pack designed for 1.16.5 might work for 1.16.1. This is because they still have some similarities in their CIT(Custom Item Texture) coding. But, be warned that it might still have glitches, bugs and might break your saved game.
It is always advised to only use the same version of texture or resource pack specifically for your game. Note that this rule does not apply to Shaders as they can mostly be used for multiple versions.