Most major anime platforms allow you to download episodes directly within their apps for offline playback at 1080p resolution. Crunchyroll

Searching for unofficial "mp4 downloads" of anime like Demon Slayer: Kimetsu no Yaiba – Yuukaku-hen (Entertainment District Arc) often leads to low-quality files or security risks. Instead, you can watch the high-quality 1080p version through several official streaming services that also offer offline viewing features for their subscribers. Official Ways to Watch and "Download" (Offline Viewing)