Trial areas vary. Fpgas are widely used, especially in the chip design phase, and most SOCs are designed with FPGas.
After the design is completed, mass production of natural SOC. In fact, FPGA was originally used to design and debug SOC circuits. Due to the large initial investment of SOC, small batch production circuits are generally completed directly with FPGas. Use SOCs in large quantities because they cost less than FPgas.