What applications are used to create such posters?

Question

Design

Are there good applications for Linux?

Answer 1

Alas, there are no applications designed for creating high-quality posters) As in any business, the main thing here is not the tool, but the idea itself.
About the execution: the most difficult thing here is to cut the girl with high quality. Everything else is just up to you. If you have a sense of composition, download handwritten fonts, arrange them as you like, and finish the rest with a brush (here a graphics tablet will come in very handy). And if you don’t have your own taste, take and copy whatever you like. After a few works, you will understand what the point is and you can make your masterpiece)
You can do everything in the same gimp. It is not as cool as Photoshop, but it does its job.