This is version 2 of my age-adjusting slider.
Good results are achieved with values ranging from -1.5 (young) to 2 (old). The slider works regardless of gender and can be used for any humanoid character.
I haven't tested the slider on anthropomorphic animal characters, but please let me know if it yields good results there as well.
This LoRA can be effectively combined with other LoRAs (e.g., character or style LoRAs).