How do I reject a call on slide to answer?

Hello Sterx,

Thanks for choosing the Apple Support Communities. Here is a set of instructions on how to decline a call on your iPhone 13 Pro max.

Answer or decline incoming calls on iPhone - Apple Support

"Silence a call

Press the side button or Sleep/Wake button (depending on your model) or either volume button.

You can still answer a silenced call until it goes to voicemail.

Decline a call and send it directly to voicemail

Do one of the following:

• Press the side button or Sleep/Wake button (depending on your model) twice quickly.
• Tap .
• Swipe up on the call banner.

You can also swipe down on the call banner for more options.

Do any of the following:

• Tap Remind Me, then choose when you want a reminder to return the call.
• Tap Message, then choose a default reply or tap Custom.
• To create your own default replies, go to Settings  > Phone > Respond with Text, then tap any default message and replace it with your own text.

Note: In some countries or regions, declined calls are disconnected without being sent to voicemail."

Cheers!