Usually, a dominant will have two voices approaching the tonic's root. Most traditionally, the leading melody comes from a semitone below, while the other (generally the bass) simply jumps between the roots:
X:1
L:1/4
M:
K:Am
%%score (T1 T2) (B1 B2)
V:T1 clef=treble
V:T2 clef=treble
V:B1 middle=d clef=bass
V:B2 middle=d clef=bass
% End of header, start of tune body:
% 1
[V:T1] "V⁷"">↑"^g, "i"a,
[V:T2] e, e,
[V:B1] d, c,
[V:B2] ">↑"e,, a,,
The other voice may also approach the root from less far away than a fourth and from above, like
X:1
L:1/4
M:
K:Am
%%score (T1 T2) (B1 B2)
V:T1 clef=treble
V:T2 clef=treble
V:B1 middle=d clef=bass
V:B2 middle=d clef=bass
% End of header, start of tune body:
% 1
[V:T1] "♯vii°⁷"">(↓)"b, "i"a,
[V:T2] f, e,
[V:B1] d, c,
[V:B2] ">↑"^g,, a,,
but this whole step down has rather less impressive leading character than a half-step, as here in the diminished seventh chord both the bass leading upwards and the alto leading down to the tonic's fifth.
The tonic's third can also be approached from a semitone above
X:1
L:1/4
M:
K:A
%%score (T1 T2) (B1 B2)
V:T1 clef=treble
V:T2 clef=treble
V:B1 middle=d clef=bass
V:B2 middle=d clef=bass
% End of header, start of tune body:
% 1
[V:T1] "V⁷"g, "I"a,
[V:T2] e, e,
[V:B1] ">↓"d, c,
[V:B2] e,, a,,
But how about the root – can this only be approached either from a semitone below or somewhere more distant? There are of course the augmented sixth chords, but these always seem to have secondary dominant function, and don't directly establish a tonic.
X:1
L:1/4
M:
K:Am
%%score (T1 T2) (B1 B2)
V:T1 clef=treble
V:T2 clef=treble
V:B1 middle=d clef=bass
V:B2 middle=d clef=bass
% End of header, start of tune body:
% 1
[V:T1] "viIt⁺⁶"a, "V"^g, "i"a,
[V:T2] ^d, e, e,
[V:B1] a,, b,, c,
[V:B2] ">↓"f,, e,, a,,