Small simple add-on for Blender 2.93.4 LTS
Adds a toggle to the Blender UI. When enabled a "Double Left Click" selects the entire collection the currently selected object is in while in object mode. I have no idea how well this works with objects that exist in multiple collections, or how things will behave with custom Keymaps, and Right Click select. If it works for you, great! If it doesn't, sorry wish I could do more, but I am not a programmer by any means. I just smash stuff together till it does what I want.
Also, I know there are other ways to achieve this without an Add-on, but this just makes it much easier.
The Add-on is free! Tip if you like, it's welcomed, but not required! Enjoy!
Link in case anyone has problems with Gumroad.