You have access to the picture editing feature as soon as you make a new picture or if you pick a picture from your gallery. Afterwards you can send it in a chat.
You have the following options when editing a picture (upper bar):
Sticker – Add stickers or masks to your picture.
Text – Add a text.
Cut – Cut your picture.
Trash can – Delete the edited picture.
Use a filter to improve your picture. Afterwards you can add a text or description and send it.
After selecting multiple pictures, you cannot use the picture editing feature anymore. n