You can enter characters using hexadecimal Unicode code points.
In the CotEditor app
on your Mac, open a document.
Move the insertion point to the location where you want to enter the character.
Choose Edit > Insert by Unicode Code Point.
Enter a code point in the field, or select a code point from the history.
Press the Return key.
Unicode character code to enter should be just hexadecimal format as well as hexadecimal code with “U+”, “0x”, or “\u” prefixes. For example, “1F603,” “U+1F603,” “0x1F603,” or “\u1F603” are valid to input “😃.”