Almost every messaging application has now added the ability to send stickers. Telegram also has a variety of stickers but they are limited to be used on Telegram.
With the use of Sticker Download Bot, Stickers from Telegram could also be used in other messaging applications. Just send any sticker to this bot and it will provide the sticker in PNG, JPEG, and WEBP formats.
These formats could be added to applications like WhatsApp in the form of stickers. If you will send a pack of stickers then it will return you the formats in a Zip file which could be directly added to WhatsApp.