As an old time ham operator, I will state that a small antenna is not a good antenna. If you make the antenna smaller than the classical dimensions, the impedance and pattern and losses all change in ways that frustrate your intentions.
Shortening an antenna, as I mentioned above, benefits from a series inductance to cancel the capacitive component. Stepping down the voltage from the source will drive the new lower impedance better than otherwise.
Realize that an antenna is part of a circuit. So if current is to flow in it, there has to be a return path. This is where a counterpoise can help. Or use a balanced configuration, which doubles the size.
Loop antennas can be small in terms of their overall dimension but will take larger area.
This subject is not a simple one. Many books have been written and many clever designs invented. You can start with a classic book called 'Antennas' written by a master of the subject, John Kraus. This book was written many years ago but its principles, like Ohms's law, still prevail.
At one time I would have recommended the Radio Amateur's Handbook or even the ARRL Antenna Book but no more; these have deteriorated to the point of misinformation. There are some engineering periodicals that occasionally treat antennas but even these have dropped in credibility. Two that come to mind are 'Microwaves and RF" and 'High Frequency Engineering'. I may have screwed up some of the titles but I hope you get the idea.
The bottom line is that there is no simple answer to the question. It depends on required antenna gain, size, impedance, pattern, bandwidth, and a bunch of other factors. Not to mention coupling methods. Or antenna arrays.