Rectangles have stopped reading as the office-only shape. Slimmer rims, warmer acetates and a slight upsweep at the outer edge have moved them into everyday wear, and they remain the easiest shape to wear with a fringe or with hair pulled back.
If you want the structure without the severity, look for a rectangle with rounded corners rather than hard ones. It softens the whole frame while keeping the line that does the work.
Round and oval faces, most reliably. The straight top line adds definition where a round face is soft, and an oval face carries almost any width. On a long face, choose a deeper rectangle so it does not make the face look longer still.
Are rectangle frames too masculine?
That depends entirely on the rim and the colour, not the shape. A thin metal rectangle in rose gold and a chunky black acetate one are the same geometry and read completely differently.
What lens colour should I pick?
Grey keeps colours truest and is the safest choice for Indian daylight. Brown lifts contrast and is kinder on overcast days and long drives. Gradient lenses are darkest at the top, which suits city wear where you still need to read a phone.