change in font size and line spacing between two sentences

Question

<style type="text/css">
*{padding: 0; margin:0;}
body{ font-family: 'Times New Roman'; }
.tc-container{width: 100%;position: relative; text-align: center;padding: 2%;}
.tc-container tr td{vertical-align: bottom;}
/*.tc-container{
width: 100%;
padding: 2%;
position: relative;
z-index: 2;
}*/
.tcmybg {
background:top center;
position: absolute;
top: 0;
left: 0;
bottom: 0;
z-index: 1;
}
.tc-container tr td h1, h2 ,h3{margin-top: 0; font-weight: normal;}
/*@media (max-width:210mm) and (min-width:297mm){
.tc-container{
margin-top: 200px;
margin-bottom: 100px;}
}*/
</style>

<?php
$certificate[0]->certificate_text = str_replace('[name]', '[name]', $certificate[0]->certificate_text);
$certificate[0]->certificate_text = str_replace('[present_address]', '[current_address]', $certificate[0]->certificate_text);
$certificate[0]->certificate_text = str_replace('[guardian]', '[guardian_name]', $certificate[0]->certificate_text);
$certificate[0]->certificate_text = str_replace('[phone]', '[mobileno]', $certificate[0]->certificate_text);
foreach ($students as $student) {
$certificate_body = "";
$certificate_body = $certificate[0]->certificate_text;
foreach ($student as $std_key => $std_value) {
if ($std_key == "dob") {
if ($std_value != "0000-00-00" && $std_value != "") {
$std_value = date($this->customlib->getSchoolDateFormat(), $this->customlib->dateYYYYMMDDtoStrtotime($std_value));
}
}
if ($std_key == "admission_date") {
if ($std_value != "0000-00-00" && $std_value != "") {
$std_value = date($this->customlib->getSchoolDateFormat(), $this->customlib->dateYYYYMMDDtoStrtotime($std_value));
}
}
if ($std_key == "created_at") {
if ($std_value != "0000-00-00" && $std_value != "") {
$std_value = date($this->customlib->getSchoolDateFormat(), $this->customlib->dateYYYYMMDDtoStrtotime($std_value));
}
}
$certificate_body = str_replace('[' . $std_key . ']', $std_value, $certificate_body);
}
?>
<div class="" style="position: relative; text-align: center; font-family: 'Times New Roman';line-height: 1.7;">
<?php if (!empty($certificate[0]->background_image)) { ?>
<img src="<?php echo base_url('uploads/certificate/' . $certificate[0]->background_image); ?>" style="width: 100%; height: 100vh" />
<?php } ?>
<table width="100%" cellspacing="0" cellpadding="0" style="position: absolute;top: 0; margin-left: auto;margin-right: auto;left: 0;right: 0;<?php echo "width:" . $certificate[0]->content_width . "px" ?>">
<tr>
<td style="position: absolute;right:0;">
<?php if ($certificate[0]->enable_student_image == 1) { ?>
<img style="position: relative; <?php echo "top:" . $certificate[0]->enable_image_height . "px" ?>;" src="<?php echo base_url($student->image); ?>" width="100" height="auto">
<?php } ?>
</td></tr>
<tr>
<td valign="top" style="text-align:left; position: relative; <?php echo "top:" . $certificate[0]->header_height . "px" ?>"><?php echo $certificate[0]->left_header ?></td>
<td valign="top" style="text-align:center; position: relative; <?php echo "top:" . $certificate[0]->header_height . "px" ?>"><?php echo $certificate[0]->center_header ?></td>
<td valign="top" style="text-align:right; position: relative; <?php echo "top:" . $certificate[0]->header_height . "px" ?>"><?php echo $certificate[0]->right_header ?></td>
</tr>
<tr>
<td colspan="3" valign="top" style="position: relative; <?php echo "top:" . $certificate[0]->content_height . "px" ?>">
<p style="font-size: 24px; text-align:left;line-height: 1.7;"><?php echo $certificate_body;?></p></td>
</tr>
<tr>
<td valign="top" style="text-align:left;position: relative; <?php echo "top:" . $certificate[0]->footer_height . "px" ?>"><?php echo $certificate[0]->left_footer ?></td>
<td valign="top" style="text-align:center;position: relative; <?php echo "top:" . $certificate[0]->footer_height . "px" ?>"><?php echo $certificate[0]->center_footer ?></td>
<td valign="top" style="text-align:right;position: relative; <?php echo "top:" . $certificate[0]->footer_height . "px" ?>"><?php echo $certificate[0]->right_footer ?></td>
</tr>
</table>
</div>

this is my code can anyone tell me how to increase font size and style and also space between two sentence