No space heater should ever be plugged into any extension cord or power strip. Ever.
I thought @Berkshiresgal might come back and clarify but until or unless she provides some indication that the heavy duty extension cord was approved or recommended by a licensed electrician I hope no one reading here thinks it’s a good idea.
My electrician hates all extension cords and I’ve spent hundreds of dollars on new receptacles to reduce my use of them after hearing of a friends house fire caused by an extension cord. 17 pets and fosters died of smoke inhalation. It’s not a risk I’d like to take.