Are there good techniques for creating high poly regions within lower poly meshes when using subdivision modifier? I have been learning to model in Blender using the subdivision modifier, cuts, and support loops. (For an example of what I mean, see this video from Arrimus 3D. I find this technique is quite good for generating smooth and interesting geometries while retaining a pretty low poly mesh to work with.
I find sometimes I would like to add a high-poly region within an otherwise low-poly mesh. Consider the following simplified example:

Here I have a somewhat low-poly cylinder, with two levels of Catmull-Clark subdivision modifier applied. I would like to add an extruded panel (seen in the bottom left of the picture). Do do this, I extrude out some faces and then beveled the corners with a few segments. The beveling tightens up the corners nicely, in effect forcing the sub-div modifier to interpolate over that smaller region.
At first glance it seems ok, but if you zoom in there are noticeable artifacts (most visible w/ the red racecar matcap, but also visible with studio lighting):

I understand that this is likely the consequence of the ngon being generated in those regions. Converting to quads is tricky in this case, because the bevel has higher geometry density than the rest of the cylinder (although I am also new to this and possibly just missing the obvious solution). If I try cutting across the corner quad I seem to get different (but still visible) visual artifacts.
I realize this is a specific instance, but there are other simpler examples of what I mean. For example, consider a scenario like this:

In the image above, I start with a low poly plane and then slice one of the interior quads. I extrude the sliced quad, convert its inner region to a circle, and then extrude once more. At first glance it looks ok, but the normals have some odd artifacts where the high-cut and low-cut regions intersect:

The effects are less pronounced in this example.
My question is: are there some general retopology techniques or guidelines I can follow in instances like this? It seems like a relatively common thing - wanting to create a more detailed region within a low-poly mesh and avoiding artifacts at the boundaries.
You can download the blend file here if you want to take a closer look: Download (800KB)
Thanks for the assistance.
So the rules for good subdivision topology, which you're violating and which are responsible for your artifacts, are:

Quads only-- no ngons, and minimal triangles.
No 6+ poles.
Put 3 and 5 poles on the most planar parts of your mesh-- definitely not at places where your mesh has a right angle.

There are other rules.  The rules only really matter for non-planar faces-- for faces that are out-of-plane with their neighboring faces-- because any verts created in the middle of a planar neighborhood will still be in-plane, and it doesn't much matter where exactly in the face they get created.  (As long as you don't have any concave faces-- when you subdivide a concave face, the subdivision-generated vert might not actually be in the bounds of your face, leading to double of the mesh and z-fighting.)
One way that good subdiv topology is sometimes communicated is, &quot;Follow your edge flow.&quot;  If you look at the top of your circle in N2RPm.png, you can see that you're just laying a grid over your circle and bridging to the edge.  &quot;Follow the edge flow&quot; isn't always very useful advice for beginners, because it's something that doesn't make sense for a while, maybe not until you're good at topo anyways, but that's a good example of not following your edge flow.
Now, given those rules, how do we bridge areas of dense verts with areas of sparse verts?  Something like this:

Notice something especially important: I bridge the higher vert count to the lower count in a planar part of the mesh.  Not where the mesh bends 90 degrees.  Notice, no ngons, no triangles.  All 3 and 5 poles are placed on planar parts of the mesh.
There are limits to bridging like this.  You can drop two verts, or multiples of that, every time you use a new edge loop.  Here, I'm bridging 16 verts to 8 verts.  But you cannot ever drop one vert-- you cannot ever, using pure quads, bridge an even number of verts to an odd number of verts.