No. But there are other ways.

We have calibrated the speed with which the speech bubbles appear to look as natural as possible. This speed cannot be changed. The rate at which the conversation moves ahead is uniform and smooth this way.

You may have felt the need to control this speed, in case you are using a very long sentence. In such a case, we recommend splitting the sentence into multiple Messages and also using Multi Choice with a single option. For example, a sentence like -

Many of you may choose to give this off in one single Message. We recommend splitting it up as:

Message 1:

Message 2:

Multi Choice with a single option:

Okay

So when you provide the option, it pauses the conversation, allowing the user to read all the messages. It also makes the bot more interactive and fun.