You're half right - you can use Red or Force AXS shifters with 11 speed Red etap mechs, but not Rival. See here
for full details from SRAM.
Grande, are you looking for a halfway-house upgrade to a full AXS groupset? In which case I suggest a Ratio
12-speed upgrade. It allows you to use a 12-speed AXS chain and cassette with your existing 11-speed mechanical shifters and derailleur (you need to modify the shifter with one of their ratchet rings to give the extra click and the right cable pull, and you can use road cassettes with your Rival 1 derailleur or change to an Eagle derailleur and cassette by modifying the derailleur cable fin too). Then you can buy the AXS shifters and derailleur later.