this is inevitable. under the condition of not increasing the power of the light source, it is impossible to increase the light spot without reducing the illumination in any case. If that is feasible, the law of conservation of energy will be overturned and perpetual motion machines can be made.
If illumination is not required, it is the easiest way to simply consider the spot size and adjust the magnifying glass distance. Although you have said not to tell you this method, I can tell you from the standpoint of a professional that this method is the best.