IMO you should gain trust of your new colleagues before you start changing things. At the very LEAST, understand the reasoning and circumstances that resulted in the status quo. Many times I see people come with an attitude towards status quo and get distracted by trying to change things too soon and too quickly that you see them stumble and have a poor onboarding experience. Understand the system and the organization for a while, ship features and fix bugs (or whatever else) with the current setup, then everyone else will trust your judgement when you make suggestions because you have skin in the game now.

This is especially important since a lot of SWE can talk through what a solid system should look like etc but have no idea how to put that in practice with the constraints of real life. The above is a good "rite of passage" to weed out those who only do the talking.