OP it's really hard.
We've never had DS tested for autism but given it runs in the family and behaviour we experienced we never felt the need to.
When it came to eating, there was a whole load of issues. Being at the table and what foods he would even eat.
I'm not sure that parents with NT kids understand how stubborn non NT kids can be.
That said, when it came to food we stuck to our guns (pretty much).
Food was to be eaten at the table. To be clear we had to make concessions on what was eaten - cheese sandwiches 3 days in a row or grilled plain chicken in a soft tortilla for a week for example.
However we did have an incentive, that if food was eaten at the table (all of it) then "supper" would be provided later (apple slices, carrot sticks, bread sticks etc) away from the table.
Every child is different and you have to find your own way, but I'd be wary of "giving in" too quickly at such a young age and maybe try to find some compromise that still reenforces "social norms".
I'm much further down the line and tbh I think it's paid dividends. Food issues are pretty minimal now and "table talk" over the years has, I feel been instrumental in helping social skills. Most importantly, DS has had to learn that "opting out" because you don't "want to" isn't an option (about family meals or anything else - so please think about the wider ramifications if you normalise a "do as you please" approach).
Caveat to all the above - autism presents in many different ways and what works for one child isn't going to work for another, but please don't underestimate what they can do when you find the right "mechanism".