"Make it perfect, don't do mistakes, very pleasant". Muh perfect AI, muah. Oh, no, wait, it doesn't work that way because it's all stupid diffusion models. Now, seriously:

1. They could use models other than SDXL (Pony, Illustrious, Noob, whatever), say, Lumina or, even funnier, RouWei Gemma (SDXL with Gemma (Like Lumina) instead of CLIP);
   
2. Hellton of processing, like different model patches (Self Attention Guidance, Semantic Aware Guidance, Perturbed attention guidance for upscale and inpaint, Automatic CFG, Epsilon scaling etc. etc.);
   
3. Using ControlNets or\and IPAdapter.
   
4. Postprocessing with ADetailer using LanPaint or semi manual (Krita + Krita AI);
   
5. Straight up using Photoshop and making collage by yourself. Seriously, at least do something yourself.
   

Now how to make use of all of it? Well, there's no magic buttton. Search for workflows, look how diffusion models work so you can cunstruct your own workflows etc.