To begin to understand the purchase and sale of virtual land, it's necessary to understand that there isn't just one Metaverse, but several. Therefore, you need to first identify which one will suit you and choose it, then make the purchase through a wallet that handles the virtual currency with which it will be paid.
Some examples of Metaverses are Decentraland and The Sandbox, which are ahead in popularity and are also the most expensive. In these, you can access land for the equivalent of $10,000 in virtual currency. Regarding the dimensions and characteristics of the land you choose, you should consider that each metaverse will have its own rules. What you can do in the multiple metaverses is build houses, buildings, provide services, etc., most of which are sold in standard sizes. The smallest plot you can purchase is 1x1, which is equivalent to 96 square meters in The Sandbox and 16 square meters in Decentraland.
To make the final purchase, you must have a digital wallet, which is also configured to seal the purchase. You must consider that each metaverse has its own currency with which you must make purchases. For example, Decentraland uses Mana and The Sandbox uses Sand, although most platforms are compatible with Ether.
Also, one of the important things to keep in mind is that the wallet must be well-secured, as this will provide proof that the buyer is indeed the owner of the land.