Choose activities that repeat weekly
A one off event introduces you to strangers. A weekly class running club choir or five a side game introduces you to the same people over and over which is how familiarity turns into friendship. Pick anything you would enjoy even if nobody spoke to you.
Introduce yourself to neighbours in the first fortnight
There is a short window after moving in when knocking on a door to say hello is completely normal. Use it. After a couple of months it feels awkward and most people never do it.
Use local networks properly
Community Facebook groups Nextdoor parkrun and local volunteering schemes are the fastest routes into an area. Volunteering in particular puts you alongside people who already know everyone.
Say yes for the first six months
Accept every invitation even the ones that do not sound appealing. Early on your job is to increase the number of connections not to filter them. Filtering comes later.
In short
Pick something weekly meet the neighbours early and say yes to everything for six months.