In the English Grammar Profile, B1 point 79 in the category of CLAUSES is defined as:
auxiliary verb ‘do’ in an affirmative declarative clause, for emphasis and affirmation.
*Note that ‘did’ for emphasis is C1.
A search in iWeb for:
1 DO KNOW 89665
2 DO GET 69098
3 DO THINK 68682
I do think that it is important for people who are being instructed in writing to know their stuff.
4 DO NEED 64647
5 DO LIKE 50742
6 DO WANT 45850
7 DO BELIEVE 42818
*However the grammar point is hidden under B1 ‘mental process verbs’
Now I still do believe in the power of the internet to bring more voices to the table.
8 DO LOVE 30323
9 DO MAKE 29862
10 DO USE 28190
11 DO FEEL 27086
12 DO FIND 24659
13 DO AGREE 22667
But I do agree that things are a mess.
The rest of the results we have have added in order with CEFR level:
add, agree, become, believe, bring, care, check, decide, follow, happen, hope, include, keep,
let, lose, matter, mean, notice, offer, own, plan, prefer, receive, sell, share, spend, try, wish
Another expert example:
That is why I do reiterate that there is no royal road to learning.