For example, if you have an adult female leopard gecko and decide to buy another one, you must first find out if the size of your terrarium is suitable for it.

A terrarium of about 40 x 40 cm is sufficient to keep one leopard gecko. So if you want to keep two together in one terrarium, the size of the terrarium should be about 80 x 40 cm. For 3 or more animals 100-120×40 cm.
Height is not crucial, because leos live in the ground zone.

Females are really peaceful, but stress can occur between them if it gets too crowded.
You also need to offer your animals enough warm and cool hiding places.

But the following must be very clear:
1- Males only single keeping!
2- Babies up to 2-3 months only single keeping!