I'm not tech-savvy, but if I build a PC, can I sync it with my laptop?

For example, if all the files on my PC desktop are saved to OneDrive,
can I immediately access and continue working on those same files from my laptop?
In other words, even if I don't manually upload them to OneDrive,
is it possible to have a setup where simply saving files to the PC automatically syncs them to OneDrive?
And if I do this, I'm wondering if I can continue my work from the PC on my laptop in real-time.
My laptop is lagging so I'm looking for a new one, but they're so expensive that I'm thinking of just buying a PC instead...