Sharding is only available for bots with premium hosting time (AKA only for premium bots).

Sharding brings automatic separation of your bot between servers in order to speed up its operations and keep it stable when it has joined a large number of guilds.

Learn more about the sharding definition on TechTarget.

As stated in our Terms Of Service, we can't guarantee you stable operation of your bot when it has joined a large number of guilds unless your bot has premium hosting time.

It should be noted that sharding doesn't allow your bot to bypass the guild cap limit which is stated in our Terms Of Service.
Once your bot reaches the guild cap limit, the bot will no longer be able to be invited to any guild, unless the bot will leave other guilds.

If you're wondering about if it's possible to increase a guild cap limit for your bot, yes it's possible.
You will have to contact the developers on this subject. But keep in mind, they may refuse for any reasons they see unfit and won't increase it for reasons like "just in advance", etc.
Also, your bot should be a premium bot in order to stably operate with a big number of guilds.