It quite easy to show Bittrex's charts in fullscreen. All you have to do is to change the word "Index" with the word "marketStandardChart" in the url of the market.
Example BTC-ETH market:
- Standard link: https://bittrex.com/market/marketStandardChart?MarketName=BTC-ETH
- Fullscreen chart link: https://bittrex.com/Market/Index?MarketName=BTC-ETH