You can change the style by wrapping the input inside a label and change the input display to none. Then, you can specify the text you want to be displayed inside a span element. Note: here I used bootstrap 4 button style (btn btn-outline-primary). You can use any style you want.
<label class="btn btn-outline-primary">
<span>Select File</span>
<input type="file">
</label>
input {
display: none;
}