Get a ring size measuring stick, put the ring on the measuring stick, then press the ring down firmly or gently tap the ring down with a tool, and try it on as it expands until the ring is the right size.
Note: Although this method can play a role in slightly expanding the ring rim to a certain extent, if it is improperly operated, it will have a significant impact on the appearance and quality of the ring.
If the ring is too small, you can take the ring to a professional jewelry store or jewelry repair shop and find a professional to modify it. Professionals usually use the gold method or thin method to make the ring size larger.
The gold method is to cut the middle of the ring, and then weld a piece of metal of the same material, and polish it to restore the ring to its original state. Thinning method is to use professional tools to thin the ring metal and increase the size.
If you have some budget, you can buy a new ring to wear.
If the ring is gold or platinum, you can take it to the jewelry store and ask if there is a trade-in service. If so, you can make up the difference and exchange it for a brand new ring. Or if the ring is still within the return period, you can ask someone at the jewelry store to help change the ring to a larger size.