I own 9k sq feet near Nashville's airport. We have 1000 members, and I am currently expanding. I am finding real estate to be the biggest hurdle to overcome when it comes to expansion, as I am currently working to expand to 14,100 sq feet in Q4 2026. I believe you can easily compete with any big box gym if you have a member culture that makes it that way.
I also believe more people who have money will train somewhere "local" over corporate gyms if the equipment is clean and up to date/usable.
With that said, we grew at 4k sq feet and expanded to 9k in the first 3 years, and it took me another 6 years to get to where I can expand again. My company stays debt-free as I live off my training income and allow the gym to do its thing as I am looking at it more of a 20-year play (10 years next April).
I believe you have to find what you want to run and enjoy running daily. The model for me started with trainers driving the culture to moving to where the members drive the culture and it's for the better of everyone as a whole when that happens.
I hope this helps, and regardless, I'm rooting for you in business and hope you kick some ass!