Welcome to Shopify Community. My name is Olivia and I work here.
Thanks for sharing your question with our network, I'd be happy to help you out. The slide cart drawer you're referring to in your image most likely has a separate liquid template that your theme's header.liquid won't cover. Typically, this will be called something along the lines of cart.liquid, but it can depend on your theme.
Please feel free to share what theme you are using with us for more accurate advice.
I look forward to connecting,
Thanks for getting back to me, @Stefan7kk.
I'm not familiar with that third-party theme as it's not one listed on our Theme Store, but it definitely sounds like you're on the right track. I hope that works, but if you run into any issues you can always connect with your theme's developer to ask any theme specific questions.