There is #ToonMe where you draw on half of your selfie to show how you'd look like in your style.
and 24 hour comic day that i need to doublecheck the exact tag for;; basically you make a couple or so of comic panels every single hour for a whole day. Quite the challenge : P
We got the #Huevember challenge in November where you mainly focus on a single hue per day.
Every second Monday of a new month is a #CelebrateCANVASDay so make sure you promote your webtoon under this hashtag for a chance to get a signal boost for your socials.
Additionally, if you update on Webtoon, make sure you promote it under #webtooncanvas as much as you can as this is the tag the Canvas creators' team check regularly.