Shimano cross compatibility

Hi there. Can somebody please help me. Can you mix and match Shimano components across the ranges. I know you can use any 11 speed components together but what about the others. Basically I am looking at a new frame but want to swap my old components over. I can’t afford a new frame and groupset all at once so that’s how it has to be. I am running Claris but want to upgrade in the future. Also currently have a sure taper bb and un named crankset. I am keen to upgrade that to a better bb and crank set in he new frame but rather than get a Claris crankset would a tiagra one work with the rest of my Claris components for the time being? That way I can upgrade the other parts of the groupset as and when, ending up with full Tiagra on a nice new frame. I have already upgraded wheels and tyres. I know buying a whole new bike would be more cost effective in the long run but I don’t have oodles of spare income to splash out in one go. Plus I want to enjoy the process of building up a bike myself. If you can build it then you can fix it.