Count characters and check them against the limits you write for - here in this tab, with nothing uploaded.
Character limits are for things you are about to publish, which means they are not published yet. This counts in the tab, and nothing is sent anywhere.
Here, yes - it is counted as you see it. Some platforms count certain emoji as two, which the X bar takes into account.
A post on X (280), a meta description (160), a title tag (60), an SMS (160) and an Instagram caption (2,200).
Both ways: the totals are shown with and without spaces.