What are some common ways snakes get in houses/ basements?

Can they gain access under the siding? If the foundation is say 2ft above ground? I cannot find an entry point! They are prairie ring neck snakes so very small

Ring necks are ground level fossorial in habit so start there. Garage doors are notorious for letting the small "ground" snakes slide under. Check all walk doors for proper weatherstripping and sweeps. Other ways the small ones enter is being brought in on items brought in for the winter.

I use my hook for more than picking up snakes. The 3/8" Ti rod is perfect for probing around doors and windows.

Unguarded floor drains are another way for them to enter as well as any pipe or vents that penetrate the foundation walls.

No doors on the basement level . windows, yes but they are 18 inches or so above ground. All pipes and utility lines are sealed tight. There was an area where stone foundation meets the concrete foundation and there were crevices . Also another area where vines and such had grown up under neath the siding . The house was vacant for 7 months . The new owners have found 6 in about 2 weeks

Stone, aka rubble foundations are almost always a source of gaps for ground dwelling snakes.