Depends what you want to do with him.
If you give him more Elemental Mastery (probably an EM Sands) you can run him in a Melt team with Bennett/Xiangling[/Thoma{requires high ER and HP investment}]/Anemo flex [Kazuha, Sucrose, Lynette, Jean)
If you want to do Freeze, you would have another Cryo for Resonance (extra Crit rate) with Xingqiu[/Ayato/Kokomi/Yelan/Barbara]/Shenhe[/Layla/Rosaria/Kaeya/Diona/Burst Ganyu]/Anemo Flex (see above, Sucrose is more useful in Melt with her EM share)
You can do Hyperfridge (Hyperbloom with a freeze element) so [Nahida/Dendro Traveler/Collei]/Xingqiu[/Yelan]/Kuki Shinobu[/Raiden Shogun on an EM build]
You can also do Mono-cryo (No reactions except Cryo Swirl) with Shenhe[/Rosaria/Kaeya/Layla/Ganyu]/[Kazuha/Lynette]/Flex (Healer required at C0 so Diona would slot in well here as would Sayu or Jean)
Another Variation for Freeze is Double Geo with Yun Jin (buffs Normal attack damage)/Zhongli[/Noelle, though not reliable]/Xingqiu[/Yelan/Kokomi]. Though do be careful with this one as he can break the Freeze status with Shatter reactions
All of these builds use 4pc Marcheussee Hunter (Atk% Sands [Freeze/Cryo/Fridge], Crit Rate or Crit DMG head piece (DMG for Freeze/Mono Cryo. Your Crit Rate before Resonance and Hunter should be around 40% ish. 50% for Fridge and Melt WITH Hunter set) & a Cryo DMG Bonus Goblet.
For Melt you can do 4PC Gilded Dreams instead to ease up on EM requirements since you'll get it from the 2pc set and the 4pc effect, though more EM is always helpful when triggering these reactions. In this case it's EM/ATK% Sands/Crit Headpiece (Whichever gets you to the 1:2 ratio, with Wrio and Widsith Crit Rate headpiece is preferred in Melt)/Cryo DMG Bonus Goblet
Personally I'm running him in a Freeze team with Ganyu/Kazuha/Kokomi