It honestly varies, I don’t believe there is a standard formula out there. Are you asking what types of equipment or how many? Also, may vary based on what your niche; do you want to have predominantly equipment or open space for a variety of modalities and training? every piece of equipment will take up floor space and reduce what’s available for other equipment and reduce open space for trainers to work with clients. You may want to do some floor planning in the space and evaluate what type of flow you’re looking to achieve.
Standard equipment expectations and typical gyms are treadmills, ellipticals, bikes, and rowing machines. However there is value to multi planar and/or low impact. I.e. arc trainers or curve treadmills. Curve treadmills cost more but are better than standard treadmills. If you’re going to offer high end you may want to consider them.
The answers you got on this thread about a year and a half ago seem like they would be applicable now, too.
So, for example, Precor has an online space planner. As you get closer to purchase, you can work directly with a salesperson, often with a visit onsite.
Another way to go is to go to a company that sources several brands of exercise equipment. Like this one. They help you with the basic layout design, and can order various items for you, compare / contrast, etc. to get the best layout for your budget and goals.