Emojis and special characters not working.

The usual keyboard shortcut to open the Emojis & Symbols panel is control+cmd+spacebar. That is what works on my M1 mini with the wireless Apple extended Bluetooth keyboard. This will only work in the body text of a new Mail compose window after you have clicked there in macOS 11.5.2.

FWIW, as far as the Global key, you have to tap it and release it quickly. If you press it too long, the Emoji panel will not open.

Please read Writing an effective Apple Support Commun… - Apple Community and then re-write your post. Please also, note that telling us "Have tried everything." tells us nothing, so please be very specific when posting. We are end users like you, Apple is simply our host and does not read these forums. In order for us to help you out, you need to help us by being specifics.

An effective post might read like, "My 2021 24" M1 based iMac running Mac OS 11.2 does not display emojis. I have tried restarting the computer normally, restarting in Safe Mode, reset the SMC several times...."

Also, have you tried:

1. Launch System Preferences. You can do so by clicking on the 'Apple' logo in the Mac menu bar at the top, then clicking 'System Preferences.'
2. In the list of available options, click on the one that says 'Keyboard.'
3. Under the 'Keyboard' tab, click on the 'Show Keyboard, Emoji & Symbol Viewers in menu bar' option.

If you have truly tried everything, there is nothing further for us to discuss here.

If not… In addition to the above questions and suggestions, does the Control-Command-Space chord show the emoji menu?

What happens exactly when you do Edit > Emoji & Symbols?