Convert laptop to PC?

Can I convert my laptop to a PC? The laptop is still very good for me, and buying a PC would be too much… Would it work that way? And my laptop doesn't have HDMI so how could I connect my PC to a screen? And… Could I somehow swap my hardware (for new ect.)? L.g. And thanks in advance!

There's a possibility that comes to my mind just really stupid.

For that you may need an HDMI to USB adapter or something.

Thanks