Does Quartus support UVM in files with .sv extension?
Quartus is for FPGA technology. AFAIK, UVM stuff is mainly used for ASIC-based designs. I will be surprised to see UVM being used for FPGA designs.
BTW, you look right in your approach to learn Verilog first then SystemVerilog and UVM later. Modelsim is the third-party simulator supported by Intel's Quartus for waveform simulations. That doesn't imply that it will run UVM on Quartus. It does have all those UVM libraries but that's because Modelsim is used in the industry for ASIC designs as well.
I hope this info helps you. You can check edaplayground for your UVM learnings.