Of course you will be visual to land at MDA.
If on an IFR approach at MDA you have the required reference you continue visually, meaning repositioning the aircraft as required to land, but you are still on the IFR procedure, just proceeding visually. You dont have to ask for this, it is assumed that passing the MDA you have the required reference. If you don't have, the missed approach is flown.
Visual approach is another thing (no need to comply with published missed approach procedure) and you have to ask for it because you fly as you like to reach the final.
Sometimes you are in a circling procedure, being in an offset final approach track and when you are visual you reposition to reach the real final to land. It could be at 3 miles, let's say, depending on the approach, and no actual circling flown at all (meaning the circling pattern) You have to reposition otherwise stabilized criteria will not be met in terms of bank at low altitude, it will be dangerous just to continue on the published final approach track. You don't ask for visual for this. You are cleared for the approach. You ask for visual to make a big shortcut, visually, but not in this case.
But what I was saying is that there are a lot of procedures, NDB, categorized as circling, but without offset from the runway track.