Some background: downward slurs used in this example
The verticals distance from a notes pitch to the slur is 12 vertical units ( 1 verticals unit is 1/16 the distance between two staff lines) - however once a notes pitch falls below the 1st staff line. The slur is inserted 12 units above the first staff line and will not follow the notes inside the staff. So for example of you had two C's inside the staff - the slurs would be placed 12 units above the staff line - not the notes. If however - you move those two C's an octave higher the slurs would then be place 12 units above the pitch of those notes.
When the pitch are different - and both notes fall inside the staff - the slur is placed above "each" note but 12 units big higher relative to the first staff line.
If the notes are above the staff - the end points of the slur each will be 12 points above each note. Hence providing an angular slur.
So the direct answer to your question is no there is not automatic way (when the notes are inside the staff to creat angular slurs that follow the notes pitch - however understanding the above explaination there is a little trick that can ease your efforts.
Let's say you have 4 notes you want to slur (g,a,b,c ) all inside the staff.
1/ highlight the notes you want slur
2/ hit option+shift+ up arrow to move the notes up and octave
3/ use the insert slur key command to insert the slur - an angular slur is inserted.
4/ shift+option+down arrow to move the notes back to original position
5/ finally either drag or nudge the slur down
If you want to drag it with the mouse - do not drag one of the handles for that will change the relative angular appearance, rather select the line of the slur and as you drag up or down you, it will not affect the angle of the slur. Also two additional tricks on the move.
A/ pressing option shift as you drag it will lock movement in only the vertical position and it will not move accidentally in the horizontal position.
B/ Do Not Use the event box to change the horizontal position of the slur - for it will flatten the slur and make a horizontal slur where the two endpoints are equal.
C/ Numerically if you want to place the slur "exactly" at the same position after the drag, look at the horizontal position in the event box before you move it. It is 12 units above the center of the note ( or 12 above notes on a staff line) or 18 above the staff line a note is sitting on. You can use the event box horizontal pos to determine this, just don't modifying using that field/parameter - only modify using drag or nudge.
In this way the angular reference of the slur is maintained and you only have the adjust the vertical position of the left side of the slur after it is inserted. All of your slurs should look perfect and more importantly be consistent in shape and form with the endpoints being 12 units above each side.
This is probably more than you wanted to know - but does considerably ease the burden of making perfect slurs...