how do you create the Lego block Hermits ?
I use Bricklink Studio (linked in my pinned post!) It's the official CAD software for virtual LEGO builds (if you've heard of Lego Digital Designer back in the day, this is basically the successor to that.)
For the exact process of how I create these builds, I usually base them on an existing skin (though Ruby here is an original based on a number of other designs (in artwork) I saw other people come up with!)
Let's take Scar's S10 POE skin as an example (typically, I use Blockbench to visualize the skins better, but NameMC will do in a pinch.)
For the torso and limbs, each layer of pixels as you go up is mapped to a plate. Due to the limited detail of the body being only 2 studs thick and the limbs being 2x2, I have to get creative with how things get represented in this build format - that's where SNOT techniques come in (Studs Not On Top.)
Over the last 5 or so years, the LEGO Group has released many brackets and other elements that have helped immensely with this build format. For instance, I can cram 1x1 plates vertically, as seen in the orange of Scar's shoes, to add that detail with the help of part #41682, and use some brackets that have been around for a while to construct his fingerless gloves.
I like to use 1x2 hinge bricks for joints (mainly hips, knees, and elbows); sometimes 2x2 turntables are used to provide upper-arm and hip rotation, but those tend to sacrifice detail. I use them only when the character doesn't have too much detail on those areas to begin with, anyway, like Pearl's S11 elbows just being bare.
You're probably noticing the T pneumatic bar clipping through the plates that are connecting it to the torso. I do have to "flub" such things a lot (especially when they hold items) because it looks unsightly with the parts removed, but the connection is meant to be plausible enough that they have a reasonable range of motion! (Ball joints were considered, but they looked strange and not very Minecrafty.)
Color palette-wise: LEGO has had a lot of colors over the years and has many transparent, reflective, and even glowing/rubber variants of many colors to pick from within BL Studio. However, I'm restricted to the palette they offer when it comes to shading, and that's part of the fun: figuring out what colors work to create a gradient, like in Pearl's hair: (Reddish Brown, Brown, Light Brown, and Medium Brown from darkest to lightest, with Chrome Silver for the hairclip.)
Speaking of the heads, they're built to 1:1 proportions with the skins' heads, so 8x8x8 (20 plates in each direction, not counting the outer layers.) Here, I mainly opt for a non-SNOT style to allow for facial expressions at the plate level, so they're not built sideways like the official sets with tiles facing forward (e.g., 21276 The Creeper) are. These are often what receive the most detail in being pixel-consistent, right down to the shading, although they also take the most time.
Side note: corners where two differently colored pixels meet at an edge on the original skin are a pain. I try to use brackets where possible to mitigate that, but sometimes one just has to choose a color and roll with it.
Props are mainly just built with whatever bricks I see fit, so it's classic LEGO (while I could have them hold such props via 1x2 bricks with pin holes or something, it would result in a loss of detail on the hands, so I sacrifice that bit of realism for the renders). Take these tools and weapons, for example:
That's pretty much it!