The question is more about how to compete.
For example, there are few indie games that managed to get a lot of sales because they innovated in terms of technology or ideas, like factorio or minecraft. Yet those games are pretty ugly, they're not "HD", while there are too many indie games that are HD with high poly graphics.
Indie devs don't have money, so they obviously cannot compete on the art and content. They have to make games nobody is making, and not hesitate to make pixel art or low poly content to concentrate on the gameplay. They cannot compete with big studios on content. It's too time-expensive.
This is the most important thing that people forget about games: the content doesn't matter. 3D artists don't matter. Games are not CG movies. Unless you're Kojima or final fantasy, nobody cares about cinematics. Game developers must focus on the gameplay and stop advertising about fancy graphics. This is a never-ending problem of video games since the 3D era: too much focus on the graphics, and no efforts on the gameplay, game balance, game theory, mechanics, reward system, difficulty, game lifespan, etc.
> What engines are you suggesting
If you're not aiming for bleeding edges graphics, you can use an graphics engine, or make your own. For physics and other stuff, there are plenty of libraries. I'm just saying unreal and unity are not engines, they're framework/platforms. They impose too many contraints, and you can't do everything you want with them. Not to mention the IP or business side.