Yeah, you can, but it's a bit messy depending on what you mean by 'full book'.
For chapter-by-chapter, it's straightforward. Most official manga platforms like Viz Media's Shonen Jump app or Manga Plus follow the weekly serialization model. You can read new chapters as they drop, though you need to be quick because only the latest few are free; older ones rotate into their subscription vault. I find the app easiest for this—download chapters for the commute, which is perfect.
A 'full book' online is trickier. Hell's Paradise: Jigokuraku is a completed series, so you'd think there'd be a digital omnibus. But official sites usually sell volumes, not the whole series as one file. You'd have to buy each volume digitally from Amazon, Google Books, or the like. Some subscription services like Shonen Jump's $2/month plan give you access to their whole backlog, which is the closest to reading the 'full book' online without buying piecemeal. Just log in and binge.
Unofficial aggregator sites often have the whole thing slapped together, but the translation quality wobbles and the pages are littered with pop-ups. I used one when I was desperate around volume 6, but the official translation is way more consistent for Gabimaru and Sagiri's dialogue.
Ended up subscribing to Shonen Jump. Cheaper than collecting the physical volumes, and I can jump between the app on my tablet and the browser on my laptop without losing my place.