A well known study on a large technology firm's workforce found that employees seated within about 25 feet of a high performer got measurably better at their own jobs, with nothing formal happening between them at all.
Why proximity does this
Research on workplace peer effects, including studies on retail and manufacturing teams, keeps finding the same pattern, worker output moves in the direction of the people who can see them working, not the people who cannot. Skill and standards appear to transfer through ordinary daily contact, not through structured mentorship. Who sits near you, who you check your work against, and who you spend the most unplanned time with functions as a slow, constant influence on how good you get, whether or not anyone intends it that way.
Where this gets skipped
Deliberately seeking out people who make you feel slightly out of your depth requires initiating contact with someone new, which is a cost that a smaller, more settled circle of familiar colleagues does not require. That makes it an easy thing to postpone indefinitely rather than a decision anyone makes on purpose to avoid.
Where to start
Name the person at your workplace whose standards are visibly higher than yours in some specific way. Find one ordinary, low-stakes reason to be near them more, reviewing the same document, sitting in on the same call, not a formal mentorship ask.
The research suggests the proximity itself, not a structured arrangement, is doing most of the work.
Reading who at your specific workplace would actually raise your standard, versus who would just be uncomfortable to be around, is a judgment only you can make. What this gives you is the reason proximity alone is worth engineering, even without a formal reason attached to it.
There is a specific way to create that proximity without it looking like you are angling for attention from someone senior, and it is worth thinking through before you approach it.