This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
恗 combines the heart radical 忄 with the phonetic component 夸, but the exact historical development and original meaning are uncertain.
With a heart 忄 beside 夸, imagine a heart that is exaggerated or boastful, but since the meaning is unclear, treat this as a loose visual hint.
For コ, picture a small child (子, こ) feeling proud and showing off: 子 -> コ, and the heart 忄 is full of boastful pride.