I guess this is a beginners question. I have two pipes/lines that don't intersect. Let's say I want to connect the endpoints of the lines using two circular arcs with different radii, bend angles, that lie in different planes, but each plane lie in its respective line that I'm trying to connect.

Q1: Can solidworks somehow figure out the plane's angles, the bend angles, and bend radii so that the two bends become tangent?

Q2: if I'm limited to fixed set of radii (50, 55, 60 etc), can SW figure out which combination of bend radii, bend angles, and plane angles, so that I come as close to tangent as possible?

In the attached picture,I have created two curves (circular arcs) and I have manually tried to fit them together so they are close to tangent.

Ad Q1.

Yes

Ad. Q2

SolidWorks is not Galadriel - he doesn't read your mind. You must have some sketch assumptions (dimensions). When you specify them in a sketch, SW will not only "come as close to tangent", but will give it (In fact, Gandalf would do it - but White, Gray was too weak. But don't tell anyone about it)