we tend to bring our basil in once the weather becomes less summery (often quite early on in our region) and it survives most of the winter in the bathroom window. Then resow in the spring. Alternatively, buy a pot from Lidl’s veg counter in the spring, divide it up into individual pots and keep going with it. We don’t use enormous amounts of basil so that’s often enough for us.
As an aside Greek/dwarf basil is a lot more robust than the bigger leaved “normal” varieties.
The “buy a pot from a supermarket” method is the one I used, and it was very successful. If I’d started earlier in the year, it would have been even better.
Many supermarkets have it as seed labelled basilique nain and certainly the Lidl ones have an amazing germination rate, or they did this year. The leaves are small - just a bit bigger than thyme so they can be used whole. Easy to grow - sprinkle a few seeds in a pot and they go like the clappers. Maximum 6" tall in my experience so far.
Basil doesn’t actually like full sun that much. Ours lives in a pot at the foot of an ash tree an the dappled sunlight suits it perfectly and grows much better than when we put it in full sun.
The larger leaved “normal” ones can be very temperamental to get started, unlike the smaller leaved ones. Like @JaneJones I don’t have them in the sun all day - they’ve been on the (raised) terrace which has the added advantage that slugs and snails don’t seem to find them. It has sun in the moenings. The main problem I’ve found with them otherwise is that the second they venture above ground, they are grazed off so the plants never actually appear.