Depending on the source, sometimes you have no choice but to do some or all of it yourself. However for me personally, after years of transcribing by ear and trial and error, I don't want to do that anymore haha. It's a thankless job, can be arduous, and frustrating if you aren't into it. Not that I want or deserve extra like... adulation or anything LOL. But it's mostly just a skill that while worth building, is also worth skipping if possible for work flow purposes. But again, sometimes you have no choice either fully or partially.
But with that aside, yes there is a uhh, not so secret technique. Midi files. If you're old like me you are probably intimately familiar with them from the early internet days, and if not you may still be haha. Midi files contain some are all of the sources original composition to varying degrees of accuracy. Some people make them (transcribing as I said above) and some people rip them from the source audio when/if possible.
With a midi file, you can import that source into your DAW and from there work with it how you will. You can keep it very basic (which is not OCR quality) and slap some instruments where they should be and bam, you got a song. But with the source midi you can also begin to get creative and play around with it, make changes, add things, take them away, etc. Anything you can imagine I suppose. Some people may just use it as a guideline and actually play the parts themselves for humanization, idk. It just depends on you or what you are going for. And again, some people may not need a midi at all if the song isn't that complex or you are building something really different. There really is no one way to do things.
TL; DR - I rambled so here is a short breakdown. A shortcut to avoiding transcribing (writing down by ear) is to get a midi file and import it into your DAW. Not all people do this and what people do after that is sort of up to them. Midis arent always readily available and sometimes they aren't well made either so you may have to do it yourself anyway. But that shortcut is often available, especially for older game music.