You can use code to Custom CSS box to change text size in button.
#1. Primary Buttons
Use this CSS code.
[class*="sqs-button-element--primary"] {
font-size: 30px !important;
}


#2. Secondary Buttons
[class*="sqs-button-element--secondary"] {
font-size: 28px !important;
}

#3. Tertiary buttons
[class*="sqs-button-element--tertiary"] {
font-size: 40px !important;
}

#4. Specific button
First, you need to find the Button ID. In my example, it is:
- #block-03af45575bcc003a7178

Next, use this CSS code
#block-03af45575bcc003a7178 a {
font-size: 40px !important;
}
