I guess I’m going to have to start brooding them in the house this next week while we have a heat wave because there is no way to cool it down in the garage. I do put them outside in their coop run when I get home after work and on the weekend. Right now it’s 8:30 no heat lamp on and it’s 90 degrees in my garage. I wonder if I even need to turn it on tonight at all! Ugh this is frustrating!
Yeah. I turned off the heat lamp gradually. But, if its 90 in the garage, I'd say they don't need a heat lamp. I only had 2. They were in a building that has air condition and it remained about 78 or 80 at all times, plus then I had the reptile lamp for them which kept the area directly under it at 78. I didn't have any issues. I moved them back and forth between outdoors and the brooder. We had some cooler days creep in at the high of 72. Again, no issues. Chicks that are brooded by a hen don't stay under mom the whole time, just when they need warmed. I had a plastic dog crate in their outdoor set up and it had a good thick layer of shavings, plus I threw a piece of fleece in there if they needed to snuggle for extra warmth. I didn't have a stuffed animal.

I know they liked the fleece, but I never saw them too chilled. Just happy little chicks.
I would just observe them while they are outdoors when you can and see how they react. It sounds like you might have to provide cooler areas with those temps. Frozen water bottles can work to help provide some outdoor cooled options.
If they still need the brooder, if possible set it up some place where the temp can be more regulated like you suggested, in the house.
In this area, we have Amish. They buy lots of meat birds and egg layers. They don't get the chicks until they can be brooded outside maybe that's the option you go with? I know there are plenty who totally brood outside. I did it without a heat source plugged in - just natural heat. Like I mentioned above.
Whatever you choose, do what works for you while observing the chicks to see how they are acclimating.