The normal approach would be:

1. Get a college degree in the engineering field of interest.

2. Get a job as an engineer in that field.

3. Optionally, become a licensed Professional Engineer (PE) according to however that is done in your location.

It's not really like software engineering, in which liberal arts or self-taught people get to be called engineers without the matching blood, sweat, and tears.

(If all you want to do is make stuff, you could learn the requisite sciences to know how things work, teach yourself CAD to design something close enough, and then either put in the hours at community hacker spaces or contract someone overseas to actually make whatever you came up with. But, it seems like you are considering a much more serious career shift?)

As someone who went from structural engineering (in the UK) to software (in Australia) I can say that that path is trivial because it's possible to get a job in software without substantial qualifications or training. I was a self taught programmer, took a computing master's just to have a piece of paper and then started working. The reverse is much harder because you wouldn't get a job without a dedicated degree and the process of gaining your professional qualifications is very onerous. So unless you made the switch in your 20s you are going to be playing catch-up for a very long time. Just my 2c

Studied EE and went into software after college. Started out system programming and now I work on high level backend services and frontend SDKs.

I've been drown more to engines and power generation. Specifically, control systems that are able to maintain stable operation despite changing conditions.

Few pieces of software I've worked on operate as "control systems". Most have been business logic.

Lately, I've been viewing "keeping the lights on", more important that "keeping engagement up".

Maybe I'll try to get into embedded/FPGA programming. Last time I applied I got passed up due to lack of experience.

Transitioning to civil. There's a lot more laws, discipline and regulations involved as opposed to tech.

But lower pay right?

For sure. The engineering jobs typically have a lower pay and you'd have to start out as a junior, so higher income won't be a reason for the switch.

Lower pay but different sector with pension. WLB is much better overall.

Can I ask what drew you to civil?

I’m wondering if anyone goes from a high level programming such as data engineering to very low level like OS or compiler or embedded in profession. Hobbies don’t count but major OSS contributions count.

How did you achieve that? Is there any spring board profession you need to hop to and from?

it's very difficult as real engineers need to follow an ethical and moral code

I'm pretty sure many of them don't give a fuck about that, even laws.