I actually think Trump's moderate appeal was very simple:

• Be able to string together a coherent sentence, which neither Biden nor Kamala were able to do
• Acknowledge that illegal immigration is a problem and it shouldn't be so easy to get into the country (secure the border vs. deporting millions)
• Push back against woke radicalism
• Prioritize domestic affairs over international entanglements

If he just stuck to these things his popularity would be soaring.