You can insert the table in a block and set the width:
+ Step 1
#block(width: 100%, figure(
table(
columns: (auto, auto),
align: (left, right),
stroke: 0.5pt,
table.header([Reagent], [1X Volume (µL)]),
[A], [12.5],
[B], [2.5],
),
caption: [Table1],
)) <tbl>
+ Step2
Please see for more details How to make centralized formulae in enums - #2 by Andrew