Depends on what you are using them as for support. For example, Xiangling’s primary function is applying pyro to enemies with Guoba or her Pyronado, which doesn’t really need high stats for the goal of setting up a reaction if you DPS is the one inducing the damage. Some supports have effects based on their stats, such as max HP or their attack stats. Some, like Zhongli and Barbara, can get by as a low level character if given artifacts to raise HP while others, as their supports are more for helping you fix any errors you make in combat (Zhongli’s shield lasts longer than its cool down if it isn’t broken, Barbara’s passive heal is a near constantly applying effect once used). Some characters, like Fischl, work better if raised like they were a DPS character, especially her electro damage or attack stats.