Drizzling will definitely improve the profile of your stars, and they should all end up more round. How round will depend on how well you've managed tilt in your system, but generally the blockiness of coarse resolution stars will be mitigated or eliminated with drizzling. Elongated stars won't magically become round with drizzling, but the edges will become softer and smoother. Round still requires good tilt and optical aberration management.
As for tight, small....drizzling can potentially improve real-world resolution, with enough good quality data, and a more significant drop shrink. The drop shrink affects how spread out the drizzled information is actually drizzled. A drop shrink of 1.0 (at least in PixInsight) basically means no improvement in real-world resolution, 0.5 would potentially mean a 50% reduction in the size of details. Whether you can actually realize this potential, however, depends on the data...if the source data is soft with bloated details, drizzling, even with a significant drop shrink like 0.5, will not actually change much, if anything. If you have very crisp, sharp, detailed source data, then drop shrink will usually be able to eek out greate rimprovements in resolution.
That said, its not a magic bullet, and it really depends a lot on the data and kind of details you are drizzling. In my experience, a drop shrink of 0.5 with very good data, produces a notable but not hugely significant improvement in the fineness of the details I was able to capture. I also find that drizzling, performing careful and moderate deconvolution on the full size drizzled image to tighten things up just a bit more, then downsampling back to the original native camera resolution, nets the best results. You are really able to see the improvements that drizzling and deconvolution can deliver when you do that.