Without more context, the direct answer to "is it possible to generate a keybinding for
C-=" is "Yes".
(global-set-key (kbd "C-=") (lambda () (interactive) (message "Hello world!")))
There are many other ways. For instance, my init contains the following
:bind (("C-=" . er/expand-region)
("C-+" . er/contract-region)))
Both of these define global keybindings.
Key map specific bindings can be defined like you state in the question. An example of this, again taken from my init, defines the
<insert> key to insert an Org structure template only for buffers with Org mode enabled:
(define-key org-mode-map (kbd "<insert>") 'org-insert-structure-template)