The only thing that works for me is DIY tips.
I buy Comply 600 Core Series (size medium), tear the comply foam off the plastic tube, then place the foam around the Apple silicone tips (size large).
None of the Apple tips on their own seal correctly, nor do any of the numerous third-party tips that I've tried, including hybrid silicone/foam tips.
I get about 6 months out of the foam and they fit in the charging case modified like this.
I tried that one too but they'd squeeze themselves out as the Apple tips' silicon is the smoothest substance known to humanity.