What would be the down sides to doing printing in a hot central Texas garage? I have my first printer on the way and really don’t want to set it up in the house.

Find anther spot.  TX gets damn hot, so I would imagine that would mess with your PLA storage and melt your PLA.

Might be useful if you are printing with ABS or Nylon or something but not for PLA.

My completely uneducated concern would be as you build up the lower portions don't have time to cool and may collapse.

But I have zero experience or idea what I'm talking about here.

What type of printer? Resin? FFF? Really depends on the material, but generally humidity is not your friend, neither are temp swings if you’re running a long print. Resin printers with UV LCD screens have a tendency to overheat during long prints so that could be problematic.

Your best bet is to find a corner of your house with low airflow, temp stability and print there.

If it's something like an ender 3 than I'd just put it somewhere in the house. They're not that big.

You can make it nearly silent with a mainboard upgrade too if it doesn't already have the good one.

It might not be a problem. I have prints out in my hot garage right now. Not the printer but the prints. It's gotten in the 90s and nothing has happened to them. Direct sunlight is another issue. Still fixing my Mandalorian helmet that some seams opened up on because I'm a dumbass and forgot it on the front porch.

Temp swings will make things more difficult, especially on long prints.  Do your research.  I don't own one yet, but I've done a fair amount of reading.

You’d Probly sweat your balls off

I don't mind the noise from the printer. Printing often enough, one can tell if there's a problem just by the sound the printer makes.

I cut my teeth on an old MakerBot Rep 2x and the thing would make strange sounds depending on the type of failure. That MakerBot was an unreliable monster. Never really knew how it was going to screw up mid print. My Zortrax simply doesn't fail, I'm sure Ender 3s are the same way.

If OP bought a resin printer I can see wanting it out of the house. Most of the UV resins out there stink and I don't have much confidence in the low odor "green" resins yet.

Probably not the best thing for the electronics.

My Ender 3 is handling it ok, I just had to reprint upgrade parts in ABS because the PLA parts couldn't take the heat.

What is the ambient temp out in your garage on average?    And is it pretty consistent both day to night as well as day to day and month to month?  Dialing in your printer can help you tweak things for better performance in your specific environment, but one of the most important factors for good, consistent prints is a stable ambient temperature.   Even a few degrees can change the printing properties of a specific material significantly.  

Like others have said, higher than normal ambient temps are fine for printing ABS or Nylon, they actually may be helpful.    PLA may be a problem though.  While it prints around 180-200deg F, it gets quite soft at much lower temps.  I have seen people ruin PLA Prop projects by leaving them out in the sun or in the car on a hot summer day.  PLA+ may fair better though as it prints at 210-240deg F and from what I have experienced is less susceptible to softening in above normal ambient temps.   So you may want to give that a shot.  

If you can find a place in the house for it, you are going to be better off, but if your garage isn't too warm and stays consistent, you may be alright.  However, if its humid out there, even a little bit, you are in for non stop trouble.  If you are out in the arid parts of the state, you should be fine.