Can a budget B450 motherboard with two DIMM slots support 32GB of RAM?

Yes, most budget B450 boards with two DIMM slots support up to 32GB using two 16GB sticks. Check the motherboard’s QVL and update the BIOS if it’s an old board to avoid compatibility issues. You’ll be giving up future upgrade room to 64GB, but 32GB is plenty for gaming and most work. Just buy a matched kit of 2x16GB.