Q.CANNA LILY PROPAGATION : PLACE SEEDS IN WARM WATER 24 HRS,
CAN YOU PLACE SEEDS IN HOT WATER? ONCE YOU PLANT THE SEEDS IN THE JIFFY MIX, COVER WITH PLASTIC WRAP FOR 2 WEEKS, THEN YOU REMOVE THE WRAP AND LET THE GERMINATED SEEDS GROW FOR SIX WEEKS BEFORE PLANTING IN YOUR GARDEN. IS THAT RIGHT.

Certified GKH Gardening Expert
The article says lukewarm water but hot is probably fine. It will come to room temperature anyway. Cover with plastic wrap till the plants germinate. Then you can remove the wrap and when plants are at least 6 inches in height you can move them into a pot or outdoors after the danger of frost has passed.
https://www.gardeningknowhow.com/ornamental/bulbs/canna/planting-canna-lily-seeds.htm