In principle, a USB-C power supply with a power of ≥15W is sufficient to charge the iPhone via MagSafe. The official MagSafe cables from Apple have a USB-C interface on one side, which can be plugged into the power supply unit. Charging via MagSafe is limited to 15 watts by the manufacturer.
Space-saving and good power adapters (with 20W) are available from Baseus (Super Si QUICK CHARGER), Anker (Powerport III Nano) or Aukey (Omnia Mini), for example.