My iPhone 13 Pro Max slow charge

Optimized charging in enabled on the iPhone. Please follow this path,

iPhone > Settings > Battery > Charging > either change the Charge Limit to 100% or turn off optimized charging.

Please review the Apple Support articles on battery optimization. It contains the best  current practices for battery charging.

iPhone Battery and Performance - Apple Support

Batteries - Maximizing Performance - Apple

About the battery and performance of iPhone 11 and later - Apple Support

Hello Mariefil,

In addition to Jeff Donald's comments, consider turning off Optimized Battery Charging. See this:

About Charge Limit and Optimized Battery Charging on iPhone - Apple Support

Also see:

Fast charge your iPhone - Apple Support

Good luck.

What do you mean by slow charging? Can you please describe in more detail what you’re experiencing?