Must be nice to get to pick. My whole career I've only managed to have two choices on the hook once.
1. Not applying online. I haven't submitted a single online application. It's significantly harder to get your foot in the door when you come in the front door. All of my offers have come through recruiters (shout-out to Triplebyte!) or referrals.
2. Having a track record matters. My resume contains many concrete projects which I shipped, most with an explicit business value.
3. Interview a lot. I don't have any expectation of passing 100% of my interviews, particularly because if I'm not enthusiastic about the company/role it's hard for me to fake it.
4. Become excellent at at least one aspect of interviewing. Personally, I'm excel at writing practical code under pressure. You can toss me a project and I'll have a solid prototype done much faster than you expected. A surprisingly large number of these kinds of interviews ended up with fully half the time left for me to ask questions. The companies which assessed this directly correlate with the ones where I've received the strongest offers.
5. Get good at every aspect of interviewing. Even though my strength is in practical programming/architecture (ie. actually building products) I'm also careful to maintain a solid level of competence at everything else as well. I review algorithms/data structures before any job search and can perform decently on algo questions. I make sure to research a company's principles/values (every company has these, whether explicit or implicit) before an interview and prepare appropriate behavioral examples.
6. Time things carefully. From the very start of my interview process, I've made it clear that I won't be making a final decision until a specific date. This ensures I have time to interview with all the companies I'm interested in and companies are far more likely to respect your timeline if you communicate it well before you receive an offer. Also, keep in mind different process speeds: I made sure to have my big company referrals submitted about a month before I even started talking to startups, yet my on-sites are still coming after the vast majority of my startup on-sites.
Of course, I'm leaving out (0) of being a really solid developer. If you're not really good at what you do, it's of course going to be much harder to collect multiple strong offers. If you're not yet really good, focus on that.
I could add my own story as a data point, but I doubt people want to hear another one if they’re in such denial.