Depending on what country you're in, there is probably independent builders who will build a custom PC for you. Some of them offer some parts selection and customization, others don't.

Honestly, the first question is what kinds of games do you play? Because a PC that's intended to play competitive FPS games at 4k is very different than one to play FFXIV and Civ at 1080p. If all you need is a relatively modest gaming PC, I wouldn't bother doing a custom solution at all, and just grab a prebuilt system that has the CPU and GPU you need.

If you are going custom, I second the PC Part Picker recommendation. They have guides showing completed builds that are proven to work, and you can use that as a starting point to customize. They also have a pretty helpful forum where you can show your proposed build.

Reddit's "Build a PC" group is also good, and will have pointers and videos on how to go about building one these days. If you're concerned about DOA parts, stick to reputable merchants and check their RMA policies on that before ordering. And don't order from one outside the country, returns a much bggier hassle when border crossings are involved.