Ricing Related Question

I've been ricing my desktop slowly over the years (don't have a lot of time). I've gotten it somewhat down to what I like. I use Archlinux with Open box, polybar, and rofi. I don't use a desktop environment. My question is what are my options for ricing default applications like dolphin or similar apps with default gui's (xsensors) without using a packaged desktop environment. I believe my default theme and icons are Adwaita (GTK-3)