Context dependant. I do similar to the OP. Sometimes my events have one other person, sometimes 40.
First, you have to do whatever it takes to make you able to just do things alone, frequently, and then go ahead and do things alone, frequently. Picnics, cafe co-working, reading in a lounge/cafe/bar, walks, bike rides, hikes, photo walks, star gazing, whatever. Literally anything.
You'll probably meet people while doing this. Get their contact info. Eventually, mention "oh hey I play basketball a couple times a month, want me to text you next time I'm planning?" Repeat, you have a crew or five. A couple group chats.
Then start planning bigger events. Book 8 person tables at a restaurant, then drop a note in your chat like this:
```
Reservation for 8 at UR Meat on Tuesday April whatever, 7pm, the new kbbq place near zhongxiao fuxing station.
1. komali2
2.
3.
4...
```
People will copy/paste adding their name so you can see how many seats are filled. I've tried 10 other booking platforms, apps, whatever, nothing beats the group text thing. The group chat is where shit happens.
For more casual events like picnics, just drop a maps link and a time, remind people a couple days before, day before, and day of send a pic with where you are in the park or whatever (the "final push" for people are hesitant but see that it's really real and thus come).
Repeat, scale as desired. The consistent thread is that you have to Just Do Stuff, and people have to know that you'll Just Do Stuff regardless if people come or not, so they come see you as a dependable and fun person, a great person to tag along with.