Increasing the wire diameter will not make slightest detectable difference
in performance.

But if for some reason you think an increase in length will be beneficial,
as it usually is for short antennas, then increase length by extending and
bending the ends by about 90 degrees in either the horizontal or vertical
directions.

You can extend one or both of the ends down to insulated ground level.

You can extend the ends sideways for as long as you can manage it without
any noticeable difference in performance from the whole length being in a
straight line. Perhaps the most important characteristic of the antenna, if
it is to remain balanced, is that the feedline should be attached
approximately at the centre of the overall length. But it's not critical.

There is no doubt that increasing the overall length of a dipole, by
whatever means, up to the overall length of 1/3-wavelengths at the lowest
frequency of interest, will improve performance. Particularly in
transmitting, multiband applications.
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Reg, G4FGQ