I found the best way to learn is to do. Microchip offers Development boards at widely differing price points. The cheapest way to get started is with one of their Curiosity Nano Development Boards, sporting the PIC of your choice. They include the Programmer/Debugger, so you don't need to buy a PICkit4_5 to play.

Next download the latest MPLABX (currently v6.15), XC8 Compiler (current version v2.45), and Microchip Code Configurator (MCC). Finally, go to Microchip University to learn some basic functionality.

The most important thing is to DO! As you go through MU training, have a Nano by your side connected to your computer. Actually do the exercises.

If you look through the MU offerings, there are courses on basic C language structure, commands, etc. There are examples using the different peripherals so you can see how to make UART or TIMER0 work in C. It will take time, but the resources abound to tackle even 32-bit processors. Again, learn by doing.